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<!-- Created: Fri Apr 26 21:03:50 UTC 2024 -->
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_AssetsCurrent_lbl" xml:lang="en-US">Total current assets</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_Assets_lbl" xml:lang="en-US">Total assets</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xml:lang="en-US">Total current liabilities</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StatementClassOfStockAxis_lbl" xml:lang="en-US">Class of Stock [Axis]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_StockholdersEquity_lbl" xml:lang="en-US">Total Onconetix stockholders&#8217; equity (deficit)</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xml:lang="en-US">Total liabilities, convertible redeemable preferred stock, and stockholders&#8217; equity (deficit)</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_GrossProfit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GrossProfit"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_GrossProfit_lbl" xml:lang="en-US">Gross loss</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_OperatingExpenses" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingExpenses"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_OperatingExpenses_lbl" xml:lang="en-US">Total operating expenses</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_OperatingIncomeLoss_lbl" xml:lang="en-US">Loss from operations</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_OtherNonoperatingIncomeExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_OtherNonoperatingIncomeExpense_lbl" xml:lang="en-US">Total other income (expense)</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_IncomeLossAttributableToParent_lbl" xml:lang="en-US">Loss before income taxes</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_ProfitLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProfitLoss"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_ProfitLoss_lbl" xml:lang="en-US">Net loss</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProfitLoss_lbl0" xml:lang="en-US">Net loss</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_lbl" xml:lang="en-US">Net loss attributable to common stockholders</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax_lbl" xml:lang="en-US">Total comprehensive loss attributable to common stockholders</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_SharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesOutstanding"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_SharesOutstanding_lbl" xml:lang="en-US">Balance (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharesOutstanding" xlink:to="us-gaap_SharesOutstanding_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_SharesOutstanding_lbl0" xml:lang="en-US">Balance (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharesOutstanding" xlink:to="us-gaap_SharesOutstanding_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StatementEquityComponentsAxis_lbl" xml:lang="en-US">Equity Components [Axis]</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities_lbl" xml:lang="en-US">Net cash used in operating activities</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl" xml:lang="en-US">Net cash used in investing activities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities_lbl" xml:lang="en-US">Net cash provided by financing activities</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_lbl" xml:lang="en-US">Net increase (decrease) in cash</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl" xml:lang="en-US">Cash, beginning of period</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl"/>
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    <loc xlink:type="locator" xlink:label="us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract"/>
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    <loc xlink:type="locator" xlink:label="us-gaap_AccountingPoliciesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountingPoliciesAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountingPoliciesAbstract_lbl" xml:lang="en-US">Accounting Policies [Abstract]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_StatementGeographicalAxis_lbl" xml:lang="en-US">Geographical [Axis]</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_OtherLiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilitiesCurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_OtherLiabilitiesCurrent_lbl" xml:lang="en-US">Total</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherLiabilitiesCurrent" xlink:to="us-gaap_OtherLiabilitiesCurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis_lbl" xml:lang="en-US">Fair Value Hierarchy and NAV [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfActivityForTheSubscriptionAgreementLiabilityAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfActivityForTheSubscriptionAgreementLiabilityAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfActivityForTheSubscriptionAgreementLiabilityAbstract_lbl" xml:lang="en-US">Schedule of Activity for the Subscription Agreement Liability [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfActivityForTheSubscriptionAgreementLiabilityAbstract" xlink:to="onco_ScheduleOfActivityForTheSubscriptionAgreementLiabilityAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl" xml:lang="en-US">Balance at beginning</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl0" xml:lang="en-US">Balance at ending</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FinancialInstrumentAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FinancialInstrumentAxis_lbl" xml:lang="en-US">Financial Instrument [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinancialInstrumentAxis" xlink:to="us-gaap_FinancialInstrumentAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfActivityForTheContingentWarrantLiabilityAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfActivityForTheContingentWarrantLiabilityAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfActivityForTheContingentWarrantLiabilityAbstract_lbl" xml:lang="en-US">Schedule of Activity for the Contingent Warrant Liability [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfActivityForTheContingentWarrantLiabilityAbstract" xlink:to="onco_ScheduleOfActivityForTheContingentWarrantLiabilityAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_lbl" xml:lang="en-US">Balance at beginning</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_lbl0" xml:lang="en-US">Balance at ending</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EarningsPerShareDilutedOtherDisclosuresAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDilutedOtherDisclosuresAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EarningsPerShareDilutedOtherDisclosuresAbstract_lbl" xml:lang="en-US">Schedule of Computation of Diluted Shares Outstanding [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EarningsPerShareDilutedOtherDisclosuresAbstract" xlink:to="us-gaap_EarningsPerShareDilutedOtherDisclosuresAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_lbl" xml:lang="en-US">Antidilutive Securities [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InventoryNetAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryNetAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryNetAbstract_lbl" xml:lang="en-US">Schedule of Inventories [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryNetAbstract" xlink:to="us-gaap_InventoryNetAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InventoryNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryNet"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_InventoryNet_lbl" xml:lang="en-US">Total</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryNet" xlink:to="us-gaap_InventoryNet_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_InventoryNet_lbl0" xml:lang="en-US">Inventories</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryNet" xlink:to="us-gaap_InventoryNet_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrentAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrentAbstract_lbl" xml:lang="en-US">Schedule of Prepaid Expenses and Other Current Assets [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrepaidExpenseAndOtherAssetsCurrentAbstract" xlink:to="us-gaap_PrepaidExpenseAndOtherAssetsCurrentAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl" xml:lang="en-US">Total</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:to="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl0" xml:lang="en-US">Prepaid expenses and other current assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:to="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_lbl" xml:lang="en-US">Finite-Lived Intangible Assets by Major Class [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_lbl" xml:lang="en-US">Schedule of Annual Amortization Expense [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" xlink:to="us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" xml:lang="en-US">Total</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfGoodwillAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfGoodwillAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfGoodwillAbstract_lbl" xml:lang="en-US">Schedule of Goodwill [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfGoodwillAbstract" xlink:to="onco_ScheduleOfGoodwillAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_Goodwill" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_Goodwill_lbl" xml:lang="en-US">Goodwill Beginning Balance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Goodwill" xlink:to="us-gaap_Goodwill_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_Goodwill_lbl0" xml:lang="en-US">Goodwill Ending Balance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Goodwill" xlink:to="us-gaap_Goodwill_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_Goodwill_lbl1" xml:lang="en-US">Goodwill</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Goodwill" xlink:to="us-gaap_Goodwill_lbl1"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccruedLiabilitiesCurrentAndNoncurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedLiabilitiesCurrentAndNoncurrentAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccruedLiabilitiesCurrentAndNoncurrentAbstract_lbl" xml:lang="en-US">Schedule of Accrued Expenses [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccruedLiabilitiesCurrentAndNoncurrentAbstract" xlink:to="us-gaap_AccruedLiabilitiesCurrentAndNoncurrentAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccruedLiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_AccruedLiabilitiesCurrent_lbl" xml:lang="en-US">Total</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccruedLiabilitiesCurrent" xlink:to="us-gaap_AccruedLiabilitiesCurrent_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccruedLiabilitiesCurrent_lbl0" xml:lang="en-US">Accrued expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccruedLiabilitiesCurrent" xlink:to="us-gaap_AccruedLiabilitiesCurrent_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessCombinationsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationsAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationsAbstract_lbl" xml:lang="en-US">Acquisitions [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationsAbstract" xlink:to="us-gaap_BusinessCombinationsAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AssetAcquisitionAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetAcquisitionAxis_lbl" xml:lang="en-US">Asset Acquisition [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetAcquisitionAxis" xlink:to="us-gaap_AssetAcquisitionAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessAcquisitionAxis_lbl" xml:lang="en-US">Business Acquisition [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AssetAcquisitionConsiderationTransferred" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionConsiderationTransferred"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_AssetAcquisitionConsiderationTransferred_lbl" xml:lang="en-US">Total fair value of identifiable assets acquired</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetAcquisitionConsiderationTransferred" xlink:to="us-gaap_AssetAcquisitionConsiderationTransferred_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AssetAcquisitionConsiderationTransferred_lbl0" xml:lang="en-US">Total consideration transferred</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetAcquisitionConsiderationTransferred" xlink:to="us-gaap_AssetAcquisitionConsiderationTransferred_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MeasurementInputTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_MeasurementInputTypeAxis_lbl" xml:lang="en-US">Measurement Input Type [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputTypeAxis" xlink:to="us-gaap_MeasurementInputTypeAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="srt_RangeAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_RangeAxis_lbl" xml:lang="en-US">Statistical Measurement [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RangeAxis" xlink:to="srt_RangeAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentRiskAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DerivativeInstrumentRiskAxis_lbl" xml:lang="en-US">Derivative Instrument [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeInstrumentRiskAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_lbl" xml:lang="en-US">Total assets acquired</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_lbl" xml:lang="en-US">Total liabilities assumed</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
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    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_lbl0" xml:lang="en-US">Intrinsic value of options outstanding (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl0" xml:lang="en-US">Number of Shares, Outstanding at ending</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl0"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:label="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_lbl" xml:lang="en-US">Overfunded (underfunded) status</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent" xlink:to="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent" xlink:to="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_lbl0"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanBenefitObligation" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligation_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanBenefitObligation" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligation_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_lbl" xml:lang="en-US">Defined Benefit Plan, Plan Assets Begining Balance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:label="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_lbl0" xml:lang="en-US">Defined Benefit Plan, Plan Assets Ending Balance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RetirementPlanTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RetirementPlanTypeAxis_lbl" xml:lang="en-US">Retirement Plan Type [Axis]</label>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract" xlink:to="us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:label="us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent_lbl" xml:lang="en-US">Total</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent" xlink:to="us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesCurrentAndNoncurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="dei_DocumentType" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentType"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="dei_DocumentType_lbl" xml:lang="en-US">Document Type</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_DocumentType" xlink:to="dei_DocumentType_lbl"/>
    <loc xlink:type="locator" xlink:label="dei_EntityRegistrantName" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityRegistrantName"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="dei_EntityRegistrantName_lbl" xml:lang="en-US">Entity Registrant Name</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityRegistrantName" xlink:to="dei_EntityRegistrantName_lbl"/>
    <loc xlink:type="locator" xlink:label="dei_EntityIncorporationStateCountryCode" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityIncorporationStateCountryCode"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xml:lang="en-US">Entity Incorporation, State or Country Code</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityIncorporationStateCountryCode" xlink:to="dei_EntityIncorporationStateCountryCode_lbl"/>
    <loc xlink:type="locator" xlink:label="dei_EntityFilerCategory" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityFilerCategory"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="dei_EntityFilerCategory_lbl" xml:lang="en-US">Entity Filer Category</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityFilerCategory" xlink:to="dei_EntityFilerCategory_lbl"/>
    <loc xlink:type="locator" xlink:label="dei_EntitySmallBusiness" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntitySmallBusiness"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="dei_EntitySmallBusiness_lbl" xml:lang="en-US">Entity Small Business</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntitySmallBusiness" xlink:to="dei_EntitySmallBusiness_lbl"/>
    <loc xlink:type="locator" xlink:label="dei_EntityEmergingGrowthCompany" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityEmergingGrowthCompany"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="dei_EntityEmergingGrowthCompany_lbl" xml:lang="en-US">Entity Emerging Growth Company</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityEmergingGrowthCompany" xlink:to="dei_EntityEmergingGrowthCompany_lbl"/>
    <loc xlink:type="locator" xlink:label="dei_EntityExTransitionPeriod" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityExTransitionPeriod"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="dei_EntityExTransitionPeriod_lbl" xml:lang="en-US">Entity Ex Transition Period</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityExTransitionPeriod" xlink:to="dei_EntityExTransitionPeriod_lbl"/>
    <loc xlink:type="locator" xlink:label="dei_AmendmentDescription" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_AmendmentDescription"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="dei_AmendmentDescription_lbl" xml:lang="en-US">Amendment Description</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_AmendmentDescription" xlink:to="dei_AmendmentDescription_lbl"/>
    <loc xlink:type="locator" xlink:label="dei_AmendmentFlag" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_AmendmentFlag"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="dei_AmendmentFlag_lbl" xml:lang="en-US">Amendment Flag</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_AmendmentFlag" xlink:to="dei_AmendmentFlag_lbl"/>
    <loc xlink:type="locator" xlink:label="dei_EntityCentralIndexKey" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityCentralIndexKey"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="dei_EntityCentralIndexKey_lbl" xml:lang="en-US">Entity Central Index Key</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityCentralIndexKey" xlink:to="dei_EntityCentralIndexKey_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AssetsAbstract_lbl" xml:lang="en-US">ASSETS</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_AssetsAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AssetsCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrentAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AssetsCurrentAbstract_lbl" xml:lang="en-US">Current assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetsCurrentAbstract" xlink:to="us-gaap_AssetsCurrentAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_Cash" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Cash"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_Cash_lbl" xml:lang="en-US">Cash</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Cash" xlink:to="us-gaap_Cash_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccountsReceivableNetCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xml:lang="en-US">Accounts receivable, net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsReceivableNetCurrent" xlink:to="us-gaap_AccountsReceivableNetCurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherReceivablesNetCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherReceivablesNetCurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherReceivablesNetCurrent_lbl" xml:lang="en-US">Receivable from related parties, net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherReceivablesNetCurrent" xlink:to="us-gaap_OtherReceivablesNetCurrent_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OtherReceivablesNetCurrent_lbl0" xml:lang="en-US">Receivable from related party</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherReceivablesNetCurrent" xlink:to="us-gaap_OtherReceivablesNetCurrent_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_UnlabeledAbstract" xlink:href="onco-20231231.xsd#onco_UnlabeledAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UnlabeledAbstract_lbl" xml:lang="en-US"></label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract" xlink:to="onco_UnlabeledAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PrepaidExpenseNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpenseNoncurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PrepaidExpenseNoncurrent_lbl" xml:lang="en-US">Prepaid expenses, long-term</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrepaidExpenseNoncurrent" xlink:to="us-gaap_PrepaidExpenseNoncurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xml:lang="en-US">Property and equipment, net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentNet" xlink:to="us-gaap_PropertyPlantAndEquipmentNet_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredCosts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredCosts"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredCosts_lbl" xml:lang="en-US">Deferred offering costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredCosts" xlink:to="us-gaap_DeferredCosts_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xml:lang="en-US">Operating right of use asset</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseRightOfUseAsset" xlink:to="us-gaap_OperatingLeaseRightOfUseAsset_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" xml:lang="en-US">Intangible assets, net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:to="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UnlabeledAbstract0" xlink:href="onco-20231231.xsd#onco_UnlabeledAbstract0"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract0" xlink:to="onco_UnlabeledAbstract0_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xml:lang="en-US">LIABILITIES, REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS&#8217; EQUITY (DEFICIT)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl" xml:lang="en-US">Current liabilities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_LiabilitiesCurrentAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccountsPayableCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableCurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xml:lang="en-US">Accounts payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableCurrent" xlink:to="us-gaap_AccountsPayableCurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NotesPayableCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NotesPayableCurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NotesPayableCurrent_lbl" xml:lang="en-US">Notes payable, net of debt discount of $381,627</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NotesPayableCurrent" xlink:to="us-gaap_NotesPayableCurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_NotesPayableNetOfDebtDiscount" xlink:href="onco-20231231.xsd#onco_NotesPayableNetOfDebtDiscount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_NotesPayableNetOfDebtDiscount_lbl" xml:lang="en-US">Notes payable, net of debt discount (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_NotesPayableNetOfDebtDiscount" xlink:to="onco_NotesPayableNetOfDebtDiscount_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xml:lang="en-US">Operating lease liability, current</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiabilityCurrent" xlink:to="us-gaap_OperatingLeaseLiabilityCurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DerivativeLiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DerivativeLiabilitiesCurrent_lbl" xml:lang="en-US">Contingent warrant liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeLiabilitiesCurrent" xlink:to="us-gaap_DerivativeLiabilitiesCurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UnlabeledAbstract1" xlink:href="onco-20231231.xsd#onco_UnlabeledAbstract1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UnlabeledAbstract1_lbl" xml:lang="en-US"></label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract1" xlink:to="onco_UnlabeledAbstract1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LongTermNotesPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermNotesPayable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LongTermNotesPayable_lbl" xml:lang="en-US">Note payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermNotesPayable" xlink:to="us-gaap_LongTermNotesPayable_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_LongTermNotesPayable_lbl0" xml:lang="en-US">Loan payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermNotesPayable" xlink:to="us-gaap_LongTermNotesPayable_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_SubscriptionAgreementLiabilityNoncurrent" xlink:href="onco-20231231.xsd#onco_SubscriptionAgreementLiabilityNoncurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SubscriptionAgreementLiabilityNoncurrent_lbl" xml:lang="en-US">Subscription agreement liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SubscriptionAgreementLiabilityNoncurrent" xlink:to="onco_SubscriptionAgreementLiabilityNoncurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xml:lang="en-US">Operating lease liability, net of current portion</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:to="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet_lbl" xml:lang="en-US">Deferred tax liability, net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:to="us-gaap_DeferredIncomeTaxLiabilitiesNet_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UnlabeledAbstract2" xlink:href="onco-20231231.xsd#onco_UnlabeledAbstract2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UnlabeledAbstract2_lbl" xml:lang="en-US"></label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract2" xlink:to="onco_UnlabeledAbstract2_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommitmentsAndContingencies" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingencies"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xml:lang="en-US">Commitments and Contingencies (see Note 10)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommitmentsAndContingencies" xlink:to="us-gaap_CommitmentsAndContingencies_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UnlabeledAbstract3" xlink:href="onco-20231231.xsd#onco_UnlabeledAbstract3"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UnlabeledAbstract3_lbl" xml:lang="en-US"></label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract3" xlink:to="onco_UnlabeledAbstract3_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl" xml:lang="en-US">Series B Convertible Redeemable Preferred stock, $0.00001 par value, 2,700,000 and 0 shares authorized at December 31, 2023 and 2022, respectively; 2,696,729 and 0 shares issued and outstanding at December 31, 2023 and 2022, respectively</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:to="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TemporaryEquityParOrStatedValuePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquityParOrStatedValuePerShare"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_TemporaryEquityParOrStatedValuePerShare_lbl" xml:lang="en-US">Convertible redeemable preferred stock, par value (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquityParOrStatedValuePerShare" xlink:to="us-gaap_TemporaryEquityParOrStatedValuePerShare_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TemporaryEquitySharesAuthorized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquitySharesAuthorized"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_TemporaryEquitySharesAuthorized_lbl" xml:lang="en-US">Convertible redeemable preferred stock, shares authorized</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquitySharesAuthorized" xlink:to="us-gaap_TemporaryEquitySharesAuthorized_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TemporaryEquitySharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquitySharesIssued"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_TemporaryEquitySharesIssued_lbl" xml:lang="en-US">Convertible redeemable preferred stock, shares issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquitySharesIssued" xlink:to="us-gaap_TemporaryEquitySharesIssued_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TemporaryEquitySharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_TemporaryEquitySharesOutstanding_lbl" xml:lang="en-US">Convertible redeemable preferred stock, shares outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquitySharesOutstanding" xlink:to="us-gaap_TemporaryEquitySharesOutstanding_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquityAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xml:lang="en-US">Stockholders&#8217; equity (deficit)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_StockholdersEquityAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockValue_lbl" xml:lang="en-US">Series A Convertible Preferred stock, $0.00001 par value, 10,000 and 0 shares authorized at December 31, 2023 and 2022, respectively; 3,000 and 0 shares issued and outstanding at December 31, 2023 and 2022, respectively; Liquidation preference of $3,000,000 and $0 at December 31, 2023 and 2022, respectively.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockValue" xlink:to="us-gaap_PreferredStockValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl" xml:lang="en-US">Preferred stock, par value (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockParOrStatedValuePerShare" xlink:to="us-gaap_PreferredStockParOrStatedValuePerShare_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare_lbl0" xml:lang="en-US">Liquidation preference (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockParOrStatedValuePerShare" xlink:to="us-gaap_PreferredStockParOrStatedValuePerShare_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesAuthorized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl" xml:lang="en-US">Preferred stock, shares authorized</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesAuthorized" xlink:to="us-gaap_PreferredStockSharesAuthorized_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl0" xml:lang="en-US">Preferred stock, shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesAuthorized" xlink:to="us-gaap_PreferredStockSharesAuthorized_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesIssued"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xml:lang="en-US">Preferred stock, shares issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesIssued" xlink:to="us-gaap_PreferredStockSharesIssued_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_PreferredStockSharesIssued_lbl0" xml:lang="en-US">Issuance shares (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesIssued" xlink:to="us-gaap_PreferredStockSharesIssued_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/netLabel" xlink:label="us-gaap_PreferredStockSharesIssued_lbl1" xml:lang="en-US">Preferred stock, share issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesIssued" xlink:to="us-gaap_PreferredStockSharesIssued_lbl1"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl" xml:lang="en-US">Preferred stock shares outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesOutstanding" xlink:to="us-gaap_PreferredStockSharesOutstanding_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl0" xml:lang="en-US">Preferred investment options outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesOutstanding" xlink:to="us-gaap_PreferredStockSharesOutstanding_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockLiquidationPreferenceValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockLiquidationPreferenceValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockLiquidationPreferenceValue_lbl" xml:lang="en-US">Preferred stock, liquidation preference (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockLiquidationPreferenceValue" xlink:to="us-gaap_PreferredStockLiquidationPreferenceValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockValue_lbl" xml:lang="en-US">Common stock, $0.00001 par value, 250,000,000 shares authorized at December 31, 2023 and 2022; 22,841,975 and 15,724,957 shares issued at December 31, 2023 and 2022, respectively; 22,324,576 and 15,265,228 shares outstanding at December 31, 2023 and 2022, respectively</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockValue" xlink:to="us-gaap_CommonStockValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xml:lang="en-US">Common stock, par value (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockParOrStatedValuePerShare" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl0" xml:lang="en-US">Par value (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockParOrStatedValuePerShare" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesAuthorized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xml:lang="en-US">Common stock, shares authorized</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesAuthorized" xlink:to="us-gaap_CommonStockSharesAuthorized_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesIssued"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xml:lang="en-US">Common stock, shares issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesIssued" xlink:to="us-gaap_CommonStockSharesIssued_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CommonStockSharesIssued_lbl0" xml:lang="en-US">Number of shares of common stock issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesIssued" xlink:to="us-gaap_CommonStockSharesIssued_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xml:lang="en-US">Common stock, shares outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesOutstanding" xlink:to="us-gaap_CommonStockSharesOutstanding_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapital" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapital"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AdditionalPaidInCapital_lbl" xml:lang="en-US">Additional paid-in-capital</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdditionalPaidInCapital" xlink:to="us-gaap_AdditionalPaidInCapital_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TreasuryStockCommonShares" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_TreasuryStockCommonShares_lbl" xml:lang="en-US">Treasury stock, shares of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TreasuryStockCommonShares" xlink:to="us-gaap_TreasuryStockCommonShares_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xml:lang="en-US">Accumulated deficit</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" xml:lang="en-US">Accumulated other comprehensive income</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MinorityInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterest"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_MinorityInterest_lbl" xml:lang="en-US">Non-controlling interest</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MinorityInterest" xlink:to="us-gaap_MinorityInterest_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_Revenues" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_Revenues_lbl" xml:lang="en-US">Revenue</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Revenues" xlink:to="us-gaap_Revenues_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_Revenues_lbl0" xml:lang="en-US">Total revenue</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Revenues" xlink:to="us-gaap_Revenues_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CostOfRevenue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfRevenue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CostOfRevenue_lbl" xml:lang="en-US">Cost of revenue</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CostOfRevenue" xlink:to="us-gaap_CostOfRevenue_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UnlabeledAbstract4" xlink:href="onco-20231231.xsd#onco_UnlabeledAbstract4"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UnlabeledAbstract4_lbl" xml:lang="en-US"></label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract4" xlink:to="onco_UnlabeledAbstract4_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OperatingExpensesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingExpensesAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OperatingExpensesAbstract_lbl" xml:lang="en-US">Operating expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_OperatingExpensesAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense_lbl" xml:lang="en-US">Selling, general and administrative</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense_lbl0" xml:lang="en-US">Selling, general and administrative expense (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/netLabel" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense_lbl1" xml:lang="en-US">Selling, general, and administrative expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense_lbl1"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ResearchAndDevelopmentExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl" xml:lang="en-US">Research and development</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentExpense" xlink:to="us-gaap_ResearchAndDevelopmentExpense_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl0" xml:lang="en-US">Research and development expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentExpense" xlink:to="us-gaap_ResearchAndDevelopmentExpense_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_lbl" xml:lang="en-US">Impairment of ENTADFI assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill" xlink:to="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherAssetImpairmentCharges" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetImpairmentCharges"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherAssetImpairmentCharges_lbl" xml:lang="en-US">Impairment of deposit on asset purchase agreement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherAssetImpairmentCharges" xlink:to="us-gaap_OtherAssetImpairmentCharges_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OtherAssetImpairmentCharges_lbl0" xml:lang="en-US">Impairment charge of long-lived assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherAssetImpairmentCharges" xlink:to="us-gaap_OtherAssetImpairmentCharges_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/netLabel" xlink:label="us-gaap_OtherAssetImpairmentCharges_lbl1" xml:lang="en-US">Long-lived assets of carrying amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherAssetImpairmentCharges" xlink:to="us-gaap_OtherAssetImpairmentCharges_lbl1"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherIncomeAndExpensesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherIncomeAndExpensesAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherIncomeAndExpensesAbstract_lbl" xml:lang="en-US">Other income (expense)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherIncomeAndExpensesAbstract" xlink:to="us-gaap_OtherIncomeAndExpensesAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl" xml:lang="en-US">Loss on extinguishment of note payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:to="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl0" xml:lang="en-US">Loss on extinguishment of note payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:to="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_ChangeInFairValueOfSubscriptionAgreementLiability" xlink:href="onco-20231231.xsd#onco_ChangeInFairValueOfSubscriptionAgreementLiability"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ChangeInFairValueOfSubscriptionAgreementLiability_lbl" xml:lang="en-US">Change in fair value of subscription agreement liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ChangeInFairValueOfSubscriptionAgreementLiability" xlink:to="onco_ChangeInFairValueOfSubscriptionAgreementLiability_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueOptionChangesInFairValueGainLoss1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueOptionChangesInFairValueGainLoss1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueOptionChangesInFairValueGainLoss1_lbl" xml:lang="en-US">Change in fair value of contingent warrant liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueOptionChangesInFairValueGainLoss1" xlink:to="us-gaap_FairValueOptionChangesInFairValueGainLoss1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockDividendsIncomeStatementImpact" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendsIncomeStatementImpact"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockDividendsIncomeStatementImpact_lbl" xml:lang="en-US">Cumulative preferred stock dividends</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockDividendsIncomeStatementImpact" xlink:to="us-gaap_PreferredStockDividendsIncomeStatementImpact_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UnlabeledAbstract5" xlink:href="onco-20231231.xsd#onco_UnlabeledAbstract5"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UnlabeledAbstract5_lbl" xml:lang="en-US"></label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract5" xlink:to="onco_UnlabeledAbstract5_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EarningsPerShareBasic" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasic"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EarningsPerShareBasic_lbl" xml:lang="en-US">Net loss per share attributable to common stockholders, basic (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EarningsPerShareBasic" xlink:to="us-gaap_EarningsPerShareBasic_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EarningsPerShareDiluted" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDiluted"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EarningsPerShareDiluted_lbl" xml:lang="en-US">Net loss per share attributable to common stockholders, diluted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EarningsPerShareDiluted" xlink:to="us-gaap_EarningsPerShareDiluted_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xml:lang="en-US">Weighted average number of common shares outstanding, basic (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xml:lang="en-US">Weighted average number of common shares outstanding, diluted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UnlabeledAbstract6" xlink:href="onco-20231231.xsd#onco_UnlabeledAbstract6"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UnlabeledAbstract6_lbl" xml:lang="en-US"></label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract6" xlink:to="onco_UnlabeledAbstract6_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossTaxAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossTaxAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherComprehensiveIncomeLossTaxAbstract_lbl" xml:lang="en-US">Other comprehensive loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherComprehensiveIncomeLossTaxAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossTaxAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ChangeInPensionBenefitObligation" xlink:href="onco-20231231.xsd#onco_ChangeInPensionBenefitObligation"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ChangeInPensionBenefitObligation_lbl" xml:lang="en-US">Change in pension benefit obligation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ChangeInPensionBenefitObligation" xlink:to="onco_ChangeInPensionBenefitObligation_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl" xml:lang="en-US">Issuance of common stock in initial public offering, net of $2.9 million of offering costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:to="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl" xml:lang="en-US">Issuance of common stock in initial public offering, net of $2.9 million of offering costs (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_IssuanceOfCommonStockInInitialPublicOfferingNet" xlink:href="onco-20231231.xsd#onco_IssuanceOfCommonStockInInitialPublicOfferingNet"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_IssuanceOfCommonStockInInitialPublicOfferingNet_lbl" xml:lang="en-US">Issuance of common stock in initial public offering, net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfCommonStockInInitialPublicOfferingNet" xlink:to="onco_IssuanceOfCommonStockInInitialPublicOfferingNet_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_lbl" xml:lang="en-US">Conversion of convertible preferred stock to common stock upon initial public offering</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:to="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_lbl" xml:lang="en-US">Conversion of convertible preferred stock to common stock upon initial public offering (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:to="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodValueOfssuanceOfCommonStockAndWarrants" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodValueOfssuanceOfCommonStockAndWarrants"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodValueOfssuanceOfCommonStockAndWarrants_lbl" xml:lang="en-US">Issuance of common stock and warrants in April private placement, net of $1.1 million of offering costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueOfssuanceOfCommonStockAndWarrants" xlink:to="onco_StockIssuedDuringPeriodValueOfssuanceOfCommonStockAndWarrants_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrants" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrants"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrants_lbl" xml:lang="en-US">Issuance of common stock and warrants in April private placement, net of $1.1 million of offering costs (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrants" xlink:to="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrants_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_IssuanceOfCommonStockAndWarrantsInAprilPrivatePlacementNet" xlink:href="onco-20231231.xsd#onco_IssuanceOfCommonStockAndWarrantsInAprilPrivatePlacementNet"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_IssuanceOfCommonStockAndWarrantsInAprilPrivatePlacementNet_lbl" xml:lang="en-US">Issuance of common stock and warrants in April private placement, net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfCommonStockAndWarrantsInAprilPrivatePlacementNet" xlink:to="onco_IssuanceOfCommonStockAndWarrantsInAprilPrivatePlacementNet_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceofCommonStockandWarrantsinPrivatePlacement" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodValueIssuanceofCommonStockandWarrantsinPrivatePlacement"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceofCommonStockandWarrantsinPrivatePlacement_lbl" xml:lang="en-US">Issuance of common stock and warrants in August private placement, net of $2.2 million of offering costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueIssuanceofCommonStockandWarrantsinPrivatePlacement" xlink:to="onco_StockIssuedDuringPeriodValueIssuanceofCommonStockandWarrantsinPrivatePlacement_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrantsInAugustPrivatePlacementNet" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrantsInAugustPrivatePlacementNet"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrantsInAugustPrivatePlacementNet_lbl" xml:lang="en-US">Issuance of common stock and warrants in August private placement, net of $2.2 million of offering costs (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrantsInAugustPrivatePlacementNet" xlink:to="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrantsInAugustPrivatePlacementNet_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_IssuanceOfCommonStockAndWarrantsInPrivatePlacementNet" xlink:href="onco-20231231.xsd#onco_IssuanceOfCommonStockAndWarrantsInPrivatePlacementNet"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_IssuanceOfCommonStockAndWarrantsInPrivatePlacementNet_lbl" xml:lang="en-US">Issuance of common stock and warrants in August private placement, net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfCommonStockAndWarrantsInPrivatePlacementNet" xlink:to="onco_IssuanceOfCommonStockAndWarrantsInPrivatePlacementNet_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_lbl" xml:lang="en-US">Exercise of stock options</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:to="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl" xml:lang="en-US">Exercise of stock options (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl0" xml:lang="en-US">Number of Shares, Exercised</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl1" xml:lang="en-US">Exercisable shares of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl1"/>
    <loc xlink:type="locator" xlink:label="onco_ExerciseOfPrefundedWarrants" xlink:href="onco-20231231.xsd#onco_ExerciseOfPrefundedWarrants"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ExerciseOfPrefundedWarrants_lbl" xml:lang="en-US">Exercise of pre-funded warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ExerciseOfPrefundedWarrants" xlink:to="onco_ExerciseOfPrefundedWarrants_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ExerciseOfPrefundedWarrantsinShares" xlink:href="onco-20231231.xsd#onco_ExerciseOfPrefundedWarrantsinShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ExerciseOfPrefundedWarrantsinShares_lbl" xml:lang="en-US">Exercise of pre-funded warrants (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ExerciseOfPrefundedWarrantsinShares" xlink:to="onco_ExerciseOfPrefundedWarrantsinShares_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_lbl" xml:lang="en-US">Issuance of restricted stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross" xlink:to="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_lbl0" xml:lang="en-US">Total restricted common stock issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross" xlink:to="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_lbl" xml:lang="en-US">Issuance of restricted stock (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross" xlink:to="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_lbl0" xml:lang="en-US">Restricted common stock issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross" xlink:to="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_lbl" xml:lang="en-US">Stock-based compensation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:to="us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross_lbl" xml:lang="en-US">Stock-based compensation (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross" xlink:to="us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PurchaseOfTreasurySharesinShares" xlink:href="onco-20231231.xsd#onco_PurchaseOfTreasurySharesinShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PurchaseOfTreasurySharesinShares_lbl" xml:lang="en-US">Purchase of treasury shares (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PurchaseOfTreasurySharesinShares" xlink:to="onco_PurchaseOfTreasurySharesinShares_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UnlabeledAbstract7" xlink:href="onco-20231231.xsd#onco_UnlabeledAbstract7"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UnlabeledAbstract7_lbl" xml:lang="en-US"></label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract7" xlink:to="onco_UnlabeledAbstract7_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_IssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptions" xlink:href="onco-20231231.xsd#onco_IssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptions"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_IssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptions_lbl" xml:lang="en-US">Issuance of common stock from exercise of preferred investment options</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptions" xlink:to="onco_IssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptions_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptionsinShares" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptionsinShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptionsinShares_lbl" xml:lang="en-US">Issuance of common stock from exercise of preferred investment options (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptionsinShares" xlink:to="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptionsinShares_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueOther"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodValueOther_lbl" xml:lang="en-US">Issuance of warrants for settlement of contingent warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueOther" xlink:to="us-gaap_StockIssuedDuringPeriodValueOther_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesOther"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesOther_lbl" xml:lang="en-US">Issuance of warrants for settlement of contingent warrants (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesOther" xlink:to="us-gaap_StockIssuedDuringPeriodSharesOther_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceOfSeriesAPreferredStock" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodValueIssuanceOfSeriesAPreferredStock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceOfSeriesAPreferredStock_lbl" xml:lang="en-US">Issuance of Series A Preferred Stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueIssuanceOfSeriesAPreferredStock" xlink:to="onco_StockIssuedDuringPeriodValueIssuanceOfSeriesAPreferredStock_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfSeriesAPreferredStockinShares" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodSharesIssuanceOfSeriesAPreferredStockinShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfSeriesAPreferredStockinShares_lbl" xml:lang="en-US">Issuance of Series A Preferred Stock (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodSharesIssuanceOfSeriesAPreferredStockinShares" xlink:to="onco_StockIssuedDuringPeriodSharesIssuanceOfSeriesAPreferredStockinShares_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction_lbl" xml:lang="en-US">Issuance of common stock and Series B Preferred Stock in connection with PMX Transaction</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction" xlink:to="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction_lbl" xml:lang="en-US">Issuance of common stock and Series B Preferred Stock in connection with PMX Transaction (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction" xlink:to="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction_lbl0" xml:lang="en-US">Issuance of common stock (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction" xlink:to="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodValueAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodValueAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodValueAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction_lbl" xml:lang="en-US">Assumption of stock-based compensation plan awards in connection with PMX Transaction</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction" xlink:to="onco_StockIssuedDuringPeriodValueAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodSharesAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodSharesAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodSharesAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction_lbl" xml:lang="en-US">Assumption of stock-based compensation plan awards in connection with PMX Transaction (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodSharesAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction" xlink:to="onco_StockIssuedDuringPeriodSharesAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_lbl" xml:lang="en-US">Forfeitures of restricted stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures" xlink:to="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_lbl" xml:lang="en-US">Forfeitures of restricted stock (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures" xlink:to="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_OtherComprehensiveIncomeLossForeignCurrencyTranslationsAdjustmentTax" xlink:href="onco-20231231.xsd#onco_OtherComprehensiveIncomeLossForeignCurrencyTranslationsAdjustmentTax"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_OtherComprehensiveIncomeLossForeignCurrencyTranslationsAdjustmentTax_lbl" xml:lang="en-US">Foreign currency translation adjustment (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_OtherComprehensiveIncomeLossForeignCurrencyTranslationsAdjustmentTax" xlink:to="onco_OtherComprehensiveIncomeLossForeignCurrencyTranslationsAdjustmentTax_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockIssuedDuringPeriodValueOfChangesInPensionBenefitObligation" xlink:href="onco-20231231.xsd#onco_StockIssuedDuringPeriodValueOfChangesInPensionBenefitObligation"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockIssuedDuringPeriodValueOfChangesInPensionBenefitObligation_lbl" xml:lang="en-US">Changes in pension benefit obligation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueOfChangesInPensionBenefitObligation" xlink:to="onco_StockIssuedDuringPeriodValueOfChangesInPensionBenefitObligation_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xml:lang="en-US">Cash flows from operating activities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xml:lang="en-US">Adjustments to reconcile net loss to net cash used in operating activities:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_lbl" xml:lang="en-US">Impairment of ENTADFI assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill" xlink:to="us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueAdjustmentOfWarrants" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAdjustmentOfWarrants"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueAdjustmentOfWarrants_lbl" xml:lang="en-US">Fair value of subscription agreement liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueAdjustmentOfWarrants" xlink:to="us-gaap_FairValueAdjustmentOfWarrants_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_FairValueAdjustmentOfWarrants_lbl0" xml:lang="en-US">Warrant liability (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueAdjustmentOfWarrants" xlink:to="us-gaap_FairValueAdjustmentOfWarrants_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AmortizationOfDebtDiscountPremium" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfDebtDiscountPremium"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AmortizationOfDebtDiscountPremium_lbl" xml:lang="en-US">Amortization of debt discount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AmortizationOfDebtDiscountPremium" xlink:to="us-gaap_AmortizationOfDebtDiscountPremium_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensation"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensation_lbl" xml:lang="en-US">Stock-based compensation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensation" xlink:to="us-gaap_ShareBasedCompensation_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_GainLossOnRelatedPartyReceivable" xlink:href="onco-20231231.xsd#onco_GainLossOnRelatedPartyReceivable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_GainLossOnRelatedPartyReceivable_lbl" xml:lang="en-US">Loss on related party receivable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_GainLossOnRelatedPartyReceivable" xlink:to="onco_GainLossOnRelatedPartyReceivable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromRepaymentsOfRelatedPartyDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromRepaymentsOfRelatedPartyDebt"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromRepaymentsOfRelatedPartyDebt_lbl" xml:lang="en-US">Recovery of related party receivable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromRepaymentsOfRelatedPartyDebt" xlink:to="us-gaap_ProceedsFromRepaymentsOfRelatedPartyDebt_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xml:lang="en-US">Deferred tax benefit</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InventoryWriteDown" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryWriteDown"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_InventoryWriteDown_lbl" xml:lang="en-US">Impairment of inventory</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryWriteDown" xlink:to="us-gaap_InventoryWriteDown_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DepreciationDepletionAndAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DepreciationDepletionAndAmortization_lbl" xml:lang="en-US">Depreciation and amortization</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DepreciationDepletionAndAmortization" xlink:to="us-gaap_DepreciationDepletionAndAmortization_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AdjustmentOfWarrantsGrantedForServices" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentOfWarrantsGrantedForServices"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AdjustmentOfWarrantsGrantedForServices_lbl" xml:lang="en-US">Change in fair value of subscription agreement liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdjustmentOfWarrantsGrantedForServices" xlink:to="us-gaap_AdjustmentOfWarrantsGrantedForServices_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PensionExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PensionExpense_lbl" xml:lang="en-US">Net periodic pension benefit</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PensionExpense" xlink:to="us-gaap_PensionExpense_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IssuanceOfStockAndWarrantsForServicesOrClaims" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IssuanceOfStockAndWarrantsForServicesOrClaims"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IssuanceOfStockAndWarrantsForServicesOrClaims_lbl" xml:lang="en-US">Issuance of restricted common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IssuanceOfStockAndWarrantsForServicesOrClaims" xlink:to="us-gaap_IssuanceOfStockAndWarrantsForServicesOrClaims_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl" xml:lang="en-US">Changes in operating assets and liabilities:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:to="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInAccountsPayable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable_lbl" xml:lang="en-US">Accounts payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInAccountsPayable" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IncreaseDecreaseInAccruedLiabilities_lbl" xml:lang="en-US">Accrued expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:to="us-gaap_IncreaseDecreaseInAccruedLiabilities_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UnlabeledAbstract8" xlink:href="onco-20231231.xsd#onco_UnlabeledAbstract8"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UnlabeledAbstract8_lbl" xml:lang="en-US"></label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract8" xlink:to="onco_UnlabeledAbstract8_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_lbl" xml:lang="en-US">Cash flows from investing activities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireProductiveAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PaymentsToAcquireProductiveAssets_lbl" xml:lang="en-US">Acquisition of assets, including transaction costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquireProductiveAssets" xlink:to="us-gaap_PaymentsToAcquireProductiveAssets_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_lbl" xml:lang="en-US">Cash flows from financing activities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock_lbl" xml:lang="en-US">Proceeds from exercise of preferred investment options, net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock" xlink:to="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromStockOptionsExercised" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromStockOptionsExercised_lbl" xml:lang="en-US">Proceeds from exercise of stock options</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromStockOptionsExercised" xlink:to="us-gaap_ProceedsFromStockOptionsExercised_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceInitialPublicOffering" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceInitialPublicOffering"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromIssuanceInitialPublicOffering_lbl" xml:lang="en-US">Proceeds from issuance of common stock in initial public offering, net of underwriting discount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceInitialPublicOffering" xlink:to="us-gaap_ProceedsFromIssuanceInitialPublicOffering_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ProceedsFromIssuanceInitialPublicOffering_lbl0" xml:lang="en-US">Offering costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceInitialPublicOffering" xlink:to="us-gaap_ProceedsFromIssuanceInitialPublicOffering_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfWarrants" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceOfWarrants"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromIssuanceOfWarrants_lbl" xml:lang="en-US">Proceeds from issuance of common stock and warrants in private placements, net of placement agent discount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceOfWarrants" xlink:to="us-gaap_ProceedsFromIssuanceOfWarrants_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromWarrantExercises" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromWarrantExercises"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromWarrantExercises_lbl" xml:lang="en-US">Proceeds from exercise of pre-funded warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromWarrantExercises" xlink:to="us-gaap_ProceedsFromWarrantExercises_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl" xml:lang="en-US">Effect of exchange rate changes on cash</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:to="us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UnlabeledAbstract9" xlink:href="onco-20231231.xsd#onco_UnlabeledAbstract9"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UnlabeledAbstract9_lbl" xml:lang="en-US"></label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract9" xlink:to="onco_UnlabeledAbstract9_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncashInvestingAndFinancingItemsAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NoncashInvestingAndFinancingItemsAbstract_lbl" xml:lang="en-US">Noncash investing and financing activities:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:to="us-gaap_NoncashInvestingAndFinancingItemsAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NoncashOrPartNoncashAcquisitionInventoryAcquired1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncashOrPartNoncashAcquisitionInventoryAcquired1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NoncashOrPartNoncashAcquisitionInventoryAcquired1_lbl" xml:lang="en-US">Inventory and intangible assets acquired through issuance of notes payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NoncashOrPartNoncashAcquisitionInventoryAcquired1" xlink:to="us-gaap_NoncashOrPartNoncashAcquisitionInventoryAcquired1_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_EffectOfBusinessCombination" xlink:href="onco-20231231.xsd#onco_EffectOfBusinessCombination"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_EffectOfBusinessCombination_lbl" xml:lang="en-US">Effect of business combination (Note 5)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_EffectOfBusinessCombination" xlink:to="onco_EffectOfBusinessCombination_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ConversionOfStockAmountIssued1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockAmountIssued1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ConversionOfStockAmountIssued1_lbl" xml:lang="en-US">Settlement of note payable through issuance of Series A convertible preferred stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConversionOfStockAmountIssued1" xlink:to="us-gaap_ConversionOfStockAmountIssued1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueOfAssetsAcquired" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueOfAssetsAcquired"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueOfAssetsAcquired_lbl" xml:lang="en-US">Incremental fair value of exchanged preferred investment options</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueOfAssetsAcquired" xlink:to="us-gaap_FairValueOfAssetsAcquired_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_FairValueOfAssetsAcquired_lbl0" xml:lang="en-US">Fair value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueOfAssetsAcquired" xlink:to="us-gaap_FairValueOfAssetsAcquired_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NoncashOrPartNoncashAcquisitionPayablesAssumed1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncashOrPartNoncashAcquisitionPayablesAssumed1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NoncashOrPartNoncashAcquisitionPayablesAssumed1_lbl" xml:lang="en-US">Deferred offering costs included in accounts payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NoncashOrPartNoncashAcquisitionPayablesAssumed1" xlink:to="us-gaap_NoncashOrPartNoncashAcquisitionPayablesAssumed1_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_RecognitionOfContingentWarrantLiabilityUponIssuanceOfCommonStockInPrivatePlacement" xlink:href="onco-20231231.xsd#onco_RecognitionOfContingentWarrantLiabilityUponIssuanceOfCommonStockInPrivatePlacement"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_RecognitionOfContingentWarrantLiabilityUponIssuanceOfCommonStockInPrivatePlacement_lbl" xml:lang="en-US">Recognition of contingent warrant liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RecognitionOfContingentWarrantLiabilityUponIssuanceOfCommonStockInPrivatePlacement" xlink:to="onco_RecognitionOfContingentWarrantLiabilityUponIssuanceOfCommonStockInPrivatePlacement_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_WarrantsIssuedForSettlementOfContingentWarrants" xlink:href="onco-20231231.xsd#onco_WarrantsIssuedForSettlementOfContingentWarrants"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_WarrantsIssuedForSettlementOfContingentWarrants_lbl" xml:lang="en-US">Warrants issued for settlement of contingent warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WarrantsIssuedForSettlementOfContingentWarrants" xlink:to="onco_WarrantsIssuedForSettlementOfContingentWarrants_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="onco_WarrantsIssuedForSettlementOfContingentWarrants_lbl0" xml:lang="en-US">Warrants recognized (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WarrantsIssuedForSettlementOfContingentWarrants" xlink:to="onco_WarrantsIssuedForSettlementOfContingentWarrants_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_DeferredOfferingCostsPreviouslyPrepaid" xlink:href="onco-20231231.xsd#onco_DeferredOfferingCostsPreviouslyPrepaid"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_DeferredOfferingCostsPreviouslyPrepaid_lbl" xml:lang="en-US">Deferred offering costs previously included in prepaid expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DeferredOfferingCostsPreviouslyPrepaid" xlink:to="onco_DeferredOfferingCostsPreviouslyPrepaid_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_Exerciseofprefundedwarrants" xlink:href="onco-20231231.xsd#onco_Exerciseofprefundedwarrants"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_Exerciseofprefundedwarrants_lbl" xml:lang="en-US">Exercise of pre-funded warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_Exerciseofprefundedwarrants" xlink:to="onco_Exerciseofprefundedwarrants_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_IssuanceOfRestrictedStock" xlink:href="onco-20231231.xsd#onco_IssuanceOfRestrictedStock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_IssuanceOfRestrictedStock_lbl" xml:lang="en-US">Issuance of restricted stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfRestrictedStock" xlink:to="onco_IssuanceOfRestrictedStock_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_RestrictedStockForfeitures" xlink:href="onco-20231231.xsd#onco_RestrictedStockForfeitures"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_RestrictedStockForfeitures_lbl" xml:lang="en-US">Restricted stock forfeitures</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RestrictedStockForfeitures" xlink:to="onco_RestrictedStockForfeitures_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PaymentOfAccruedBonusThroughRelatedPartyReceivable" xlink:href="onco-20231231.xsd#onco_PaymentOfAccruedBonusThroughRelatedPartyReceivable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PaymentOfAccruedBonusThroughRelatedPartyReceivable_lbl" xml:lang="en-US">Payment of accrued bonus through related party receivable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PaymentOfAccruedBonusThroughRelatedPartyReceivable" xlink:to="onco_PaymentOfAccruedBonusThroughRelatedPartyReceivable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtConversionConvertedInstrumentAmount1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtConversionConvertedInstrumentAmount1_lbl" xml:lang="en-US">Conversion of Series Seed Preferred Stock to common stock upon initial public offering</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtConversionConvertedInstrumentAmount1" xlink:to="us-gaap_DebtConversionConvertedInstrumentAmount1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TreasuryStockValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_TreasuryStockValue_lbl" xml:lang="en-US">Treasury stock, at cost; 517,399 and 459,729 shares of common stock at December 31, 2023 and 2022, respectively</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TreasuryStockValue" xlink:to="us-gaap_TreasuryStockValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InterestExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_InterestExpense_lbl" xml:lang="en-US">Interest expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestExpense" xlink:to="us-gaap_InterestExpense_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax_lbl" xml:lang="en-US">Foreign currency translation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax" xlink:to="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:label="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax_lbl0" xml:lang="en-US">Foreign currency translation adjustment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax" xlink:to="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_PurchaseOfTreasuryShares" xlink:href="onco-20231231.xsd#onco_PurchaseOfTreasuryShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="onco_PurchaseOfTreasuryShares_lbl" xml:lang="en-US">Purchase of treasury shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PurchaseOfTreasuryShares" xlink:to="onco_PurchaseOfTreasuryShares_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_lbl" xml:lang="en-US">Loss on impairment of other long-lived assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges" xlink:to="us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesFairValueAdjustment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesFairValueAdjustment"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_LiabilitiesFairValueAdjustment_lbl" xml:lang="en-US">Change in fair value of contingent warrant liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesFairValueAdjustment" xlink:to="us-gaap_LiabilitiesFairValueAdjustment_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable_lbl" xml:lang="en-US">Accounts receivable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:to="us-gaap_IncreaseDecreaseInAccountsReceivable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInInventories" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInInventories"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_IncreaseDecreaseInInventories_lbl" xml:lang="en-US">Inventories</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInInventories" xlink:to="us-gaap_IncreaseDecreaseInInventories_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_lbl" xml:lang="en-US">Prepaid expenses and other current assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:to="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_lbl" xml:lang="en-US">Other noncurrent assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xlink:to="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireOtherProductiveAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireOtherProductiveAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_PaymentsToAcquireOtherProductiveAssets_lbl" xml:lang="en-US">Acquisition of assets, including transaction costs of $79,771</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquireOtherProductiveAssets" xlink:to="us-gaap_PaymentsToAcquireOtherProductiveAssets_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireRestrictedCertificatesOfDeposit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireRestrictedCertificatesOfDeposit"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_PaymentsToAcquireRestrictedCertificatesOfDeposit_lbl" xml:lang="en-US">Deposit made in connection with asset purchase agreement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquireRestrictedCertificatesOfDeposit" xlink:to="us-gaap_PaymentsToAcquireRestrictedCertificatesOfDeposit_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_lbl" xml:lang="en-US">Cash acquired through business combination</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:to="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireIntangibleAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireIntangibleAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_PaymentsToAcquireIntangibleAssets_lbl" xml:lang="en-US">Purchases of other long-lived assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquireIntangibleAssets" xlink:to="us-gaap_PaymentsToAcquireIntangibleAssets_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ReceivableFromRelatedParties1" xlink:href="onco-20231231.xsd#onco_ReceivableFromRelatedParties1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="onco_ReceivableFromRelatedParties1_lbl" xml:lang="en-US">Net advances to related parties</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ReceivableFromRelatedParties1" xlink:to="onco_ReceivableFromRelatedParties1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl" xml:lang="en-US">Purchases of property and equipment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PaymentsForPurchaseOfTreasuryShares" xlink:href="onco-20231231.xsd#onco_PaymentsForPurchaseOfTreasuryShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="onco_PaymentsForPurchaseOfTreasuryShares_lbl" xml:lang="en-US">Purchase of treasury shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PaymentsForPurchaseOfTreasuryShares" xlink:to="onco_PaymentsForPurchaseOfTreasuryShares_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsOfStockIssuanceCosts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsOfStockIssuanceCosts"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_PaymentsOfStockIssuanceCosts_lbl" xml:lang="en-US">Payment of deferred offering costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsOfStockIssuanceCosts" xlink:to="us-gaap_PaymentsOfStockIssuanceCosts_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PaymentsOfStockIssuanceCosts_lbl0" xml:lang="en-US">Equity issuance cost. (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsOfStockIssuanceCosts" xlink:to="us-gaap_PaymentsOfStockIssuanceCosts_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RepaymentsOfNotesPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfNotesPayable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_RepaymentsOfNotesPayable_lbl" xml:lang="en-US">Principal payment of note payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RepaymentsOfNotesPayable" xlink:to="us-gaap_RepaymentsOfNotesPayable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsForRepurchaseOfInitialPublicOffering" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForRepurchaseOfInitialPublicOffering"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_PaymentsForRepurchaseOfInitialPublicOffering_lbl" xml:lang="en-US">Payments of initial public offering costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsForRepurchaseOfInitialPublicOffering" xlink:to="us-gaap_PaymentsForRepurchaseOfInitialPublicOffering_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsForRepurchaseOfPrivatePlacement" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForRepurchaseOfPrivatePlacement"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_PaymentsForRepurchaseOfPrivatePlacement_lbl" xml:lang="en-US">Payment of private placement issuance costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsForRepurchaseOfPrivatePlacement" xlink:to="us-gaap_PaymentsForRepurchaseOfPrivatePlacement_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RelatedPartyMember_lbl" xml:lang="en-US">Related Party</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyMember" xlink:to="us-gaap_RelatedPartyMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_RelatedPartyMember_lbl0" xml:lang="en-US">Related Party [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyMember" xlink:to="us-gaap_RelatedPartyMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_SeriesBConvertibleRedeemablePreferredStockMember" xlink:href="onco-20231231.xsd#onco_SeriesBConvertibleRedeemablePreferredStockMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SeriesBConvertibleRedeemablePreferredStockMember_lbl" xml:lang="en-US">Series B Convertible Redeemable Preferred stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SeriesBConvertibleRedeemablePreferredStockMember" xlink:to="onco_SeriesBConvertibleRedeemablePreferredStockMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_SeriesAConvertiblePreferredStockMember" xlink:href="onco-20231231.xsd#onco_SeriesAConvertiblePreferredStockMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SeriesAConvertiblePreferredStockMember_lbl" xml:lang="en-US">Series A Convertible Preferred Stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SeriesAConvertiblePreferredStockMember" xlink:to="onco_SeriesAConvertiblePreferredStockMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="onco_SeriesAConvertiblePreferredStockMember_lbl0" xml:lang="en-US">Series A Convertible Preferred Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SeriesAConvertiblePreferredStockMember" xlink:to="onco_SeriesAConvertiblePreferredStockMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SeriesBPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesBPreferredStockMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SeriesBPreferredStockMember_lbl" xml:lang="en-US">Series B</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SeriesBPreferredStockMember" xlink:to="us-gaap_SeriesBPreferredStockMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SeriesBPreferredStockMember_lbl0" xml:lang="en-US">Series B Preferred Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SeriesBPreferredStockMember" xlink:to="us-gaap_SeriesBPreferredStockMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockMember_lbl" xml:lang="en-US">Preferred Stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockMember" xlink:to="us-gaap_PreferredStockMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_PreferredStockMember_lbl0" xml:lang="en-US">Preferred Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockMember" xlink:to="us-gaap_PreferredStockMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SeriesAPreferredStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SeriesAPreferredStockMember_lbl" xml:lang="en-US">Series A</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SeriesAPreferredStockMember" xlink:to="us-gaap_SeriesAPreferredStockMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SeriesAPreferredStockMember_lbl0" xml:lang="en-US">Series A Preferred Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SeriesAPreferredStockMember" xlink:to="us-gaap_SeriesAPreferredStockMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_SeriesSeedMember" xlink:href="onco-20231231.xsd#onco_SeriesSeedMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SeriesSeedMember_lbl" xml:lang="en-US">Series Seed</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SeriesSeedMember" xlink:to="onco_SeriesSeedMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockMember_lbl" xml:lang="en-US">Common Stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockMember" xlink:to="us-gaap_CommonStockMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CommonStockMember_lbl0" xml:lang="en-US">Common Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockMember" xlink:to="us-gaap_CommonStockMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AdditionalPaidInCapitalMember_lbl" xml:lang="en-US">Additional Paid-in Capital</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdditionalPaidInCapitalMember" xlink:to="us-gaap_AdditionalPaidInCapitalMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TreasuryStockCommonMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_TreasuryStockCommonMember_lbl" xml:lang="en-US">Treasury Stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TreasuryStockCommonMember" xlink:to="us-gaap_TreasuryStockCommonMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RetainedEarningsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RetainedEarningsMember_lbl" xml:lang="en-US">Accumulated Deficit</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetainedEarningsMember" xlink:to="us-gaap_RetainedEarningsMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeMember_lbl" xml:lang="en-US">Other Comprehensive Income</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ParentMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ParentMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ParentMember_lbl" xml:lang="en-US">Total Onconetix Equity (Deficit)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ParentMember" xlink:to="us-gaap_ParentMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NoncontrollingInterestMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NoncontrollingInterestMember_lbl" xml:lang="en-US">Non-controlling Interest</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NoncontrollingInterestMember" xlink:to="us-gaap_NoncontrollingInterestMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock_lbl" xml:lang="en-US">Organization and Basis of Presentation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock" xlink:to="us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SubstantialDoubtAboutGoingConcernTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubstantialDoubtAboutGoingConcernTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SubstantialDoubtAboutGoingConcernTextBlock_lbl" xml:lang="en-US">Going Concern and Management&#8217;s Plans</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubstantialDoubtAboutGoingConcernTextBlock" xlink:to="us-gaap_SubstantialDoubtAboutGoingConcernTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SignificantAccountingPoliciesTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock_lbl" xml:lang="en-US">Summary of Significant Accounting Policies</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SignificantAccountingPoliciesTextBlock" xlink:to="us-gaap_SignificantAccountingPoliciesTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfRevenueByMajorCustomersByReportingSegmentsTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRevenueByMajorCustomersByReportingSegmentsTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfRevenueByMajorCustomersByReportingSegmentsTableTextBlock_lbl" xml:lang="en-US">Schedule of Revenue by Geographical Area</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfRevenueByMajorCustomersByReportingSegmentsTableTextBlock" xlink:to="us-gaap_ScheduleOfRevenueByMajorCustomersByReportingSegmentsTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsByGeographicalAreasTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsByGeographicalAreasTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsByGeographicalAreasTableTextBlock_lbl" xml:lang="en-US">Schedule of Long-lived by Geographical Area</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsByGeographicalAreasTableTextBlock" xlink:to="us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsByGeographicalAreasTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NoncurrentAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncurrentAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NoncurrentAssets_lbl" xml:lang="en-US">Total long-lived asset</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NoncurrentAssets" xlink:to="us-gaap_NoncurrentAssets_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_lbl" xml:lang="en-US">Schedule of Fair Value of Financial Instruments Measured on a Recurring Basis</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xlink:to="us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LiabilitiesAbstract_lbl" xml:lang="en-US">Liabilities:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAbstract" xlink:to="us-gaap_LiabilitiesAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_LiabilitiesAbstract0" xlink:href="onco-20231231.xsd#onco_LiabilitiesAbstract0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_LiabilitiesAbstract0_lbl" xml:lang="en-US">Liabilities:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_LiabilitiesAbstract0" xlink:to="onco_LiabilitiesAbstract0_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_lbl" xml:lang="en-US">Schedule of Activity for the Subscription Agreement Liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:to="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues_lbl" xml:lang="en-US">Fair value upon issuance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPeriodIncreaseDecrease" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPeriodIncreaseDecrease"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPeriodIncreaseDecrease_lbl" xml:lang="en-US">Change in fair value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPeriodIncreaseDecrease" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPeriodIncreaseDecrease_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_lbl" xml:lang="en-US">Schedule of Activity for the Contingent Warrant Liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:to="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues_lbl" xml:lang="en-US">Fair value at issuance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ReclassificationToEquity" xlink:href="onco-20231231.xsd#onco_ReclassificationToEquity"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ReclassificationToEquity_lbl" xml:lang="en-US">Reclassification to equity</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ReclassificationToEquity" xlink:to="onco_ReclassificationToEquity_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock_lbl" xml:lang="en-US">Schedule of Computation of Diluted Shares Outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock" xlink:to="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl" xml:lang="en-US">Anti-dilutive securities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SupplementalBalanceSheetDisclosuresTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SupplementalBalanceSheetDisclosuresTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SupplementalBalanceSheetDisclosuresTextBlock_lbl" xml:lang="en-US">Balance Sheet Details</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SupplementalBalanceSheetDisclosuresTextBlock" xlink:to="us-gaap_SupplementalBalanceSheetDisclosuresTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfInventoryCurrentTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfInventoryCurrentTableTextBlock_lbl" xml:lang="en-US">Schedule of Inventories</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:to="us-gaap_ScheduleOfInventoryCurrentTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InventoryRawMaterials" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryRawMaterials"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_InventoryRawMaterials_lbl" xml:lang="en-US">Raw materials</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryRawMaterials" xlink:to="us-gaap_InventoryRawMaterials_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InventoryWorkInProcess" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryWorkInProcess"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_InventoryWorkInProcess_lbl" xml:lang="en-US">Work-in-process</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryWorkInProcess" xlink:to="us-gaap_InventoryWorkInProcess_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InventoryFinishedGoods" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryFinishedGoods"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_InventoryFinishedGoods_lbl" xml:lang="en-US">Finished goods</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryFinishedGoods" xlink:to="us-gaap_InventoryFinishedGoods_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock_lbl" xml:lang="en-US">Schedule of Prepaid Expenses and Other Current Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock" xlink:to="us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PrepaidInsurance" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidInsurance"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PrepaidInsurance_lbl" xml:lang="en-US">Prepaid insurance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrepaidInsurance" xlink:to="us-gaap_PrepaidInsurance_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PrepaidRent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidRent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PrepaidRent_lbl" xml:lang="en-US">Prepaid regulatory fees</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrepaidRent" xlink:to="us-gaap_PrepaidRent_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PrepaidsResearchAndDevelopment" xlink:href="onco-20231231.xsd#onco_PrepaidsResearchAndDevelopment"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PrepaidsResearchAndDevelopment_lbl" xml:lang="en-US">Prepaid research and development</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PrepaidsResearchAndDevelopment" xlink:to="onco_PrepaidsResearchAndDevelopment_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PrepaidProfessionalFees" xlink:href="onco-20231231.xsd#onco_PrepaidProfessionalFees"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PrepaidProfessionalFees_lbl" xml:lang="en-US">Prepaid professional fees</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PrepaidProfessionalFees" xlink:to="onco_PrepaidProfessionalFees_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherPrepaidExpenseCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherPrepaidExpenseCurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherPrepaidExpenseCurrent_lbl" xml:lang="en-US">Prepaid other</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherPrepaidExpenseCurrent" xlink:to="us-gaap_OtherPrepaidExpenseCurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock_lbl" xml:lang="en-US">Schedule of Intangible Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xlink:to="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_CostBasisAbstract" xlink:href="onco-20231231.xsd#onco_CostBasisAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_CostBasisAbstract_lbl" xml:lang="en-US">Cost basis:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CostBasisAbstract" xlink:to="onco_CostBasisAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_FiniteLivedIntangibleAssetCost" xlink:href="onco-20231231.xsd#onco_FiniteLivedIntangibleAssetCost"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_FiniteLivedIntangibleAssetCost_lbl" xml:lang="en-US">Cost</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_FiniteLivedIntangibleAssetCost" xlink:to="onco_FiniteLivedIntangibleAssetCost_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ImpairmentOfIntangibleAssetExcludingGoodwill" xlink:href="onco-20231231.xsd#onco_ImpairmentOfIntangibleAssetExcludingGoodwill"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ImpairmentOfIntangibleAssetExcludingGoodwill_lbl" xml:lang="en-US">Impairment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ImpairmentOfIntangibleAssetExcludingGoodwill" xlink:to="onco_ImpairmentOfIntangibleAssetExcludingGoodwill_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss_lbl" xml:lang="en-US">Effect of Currency Translation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss" xlink:to="us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" xml:lang="en-US">Intangible assets, gross</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsGross" xlink:to="us-gaap_FiniteLivedIntangibleAssetsGross_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AccumulatedAmortizationAbstract" xlink:href="onco-20231231.xsd#onco_AccumulatedAmortizationAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AccumulatedAmortizationAbstract_lbl" xml:lang="en-US">Accumulated amortization:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AccumulatedAmortizationAbstract" xlink:to="onco_AccumulatedAmortizationAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_FiniteLivedIntangibleAssetsAccumulatedAmortizationEffectOfCurrencyTranslation" xlink:href="onco-20231231.xsd#onco_FiniteLivedIntangibleAssetsAccumulatedAmortizationEffectOfCurrencyTranslation"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_FiniteLivedIntangibleAssetsAccumulatedAmortizationEffectOfCurrencyTranslation_lbl" xml:lang="en-US">Effect of Currency Translation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_FiniteLivedIntangibleAssetsAccumulatedAmortizationEffectOfCurrencyTranslation" xlink:to="onco_FiniteLivedIntangibleAssetsAccumulatedAmortizationEffectOfCurrencyTranslation_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock_lbl" xml:lang="en-US">Schedule of Annual Amortization Expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock" xlink:to="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl" xml:lang="en-US">2024</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl" xml:lang="en-US">2025</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl" xml:lang="en-US">2026</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl" xml:lang="en-US">2027</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_lbl" xml:lang="en-US">2028</label>
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    <loc xlink:type="locator" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesCustomerRelationships" xlink:href="onco-20231231.xsd#onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesCustomerRelationships"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesCustomerRelationships" xlink:to="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesCustomerRelationships_lbl"/>
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    <loc xlink:type="locator" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_lbl"/>
    <loc xlink:type="locator" xlink:label="srt_ScheduleOfCondensedIncomeStatementTableTextBlock" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfCondensedIncomeStatementTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_ScheduleOfCondensedIncomeStatementTableTextBlock_lbl" xml:lang="en-US">Schedule of Consolidated Statements of Operations and Comprehensive Loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ScheduleOfCondensedIncomeStatementTableTextBlock" xlink:to="srt_ScheduleOfCondensedIncomeStatementTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_BusinessAcquisitionsProFormaRevenue_lbl" xml:lang="en-US">Revenue</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:to="us-gaap_BusinessAcquisitionsProFormaRevenue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_lbl" xml:lang="en-US">Net loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss" xlink:to="us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_lbl"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SignificantAgreementsTextBlock_lbl" xml:lang="en-US">Significant Agreements</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SignificantAgreementsTextBlock" xlink:to="onco_SignificantAgreementsTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtDisclosureTextBlock"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtDisclosureTextBlock" xlink:to="us-gaap_DebtDisclosureTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_SubscriptionAgreementDisclosureTextBlock" xlink:href="onco-20231231.xsd#onco_SubscriptionAgreementDisclosureTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SubscriptionAgreementDisclosureTextBlock_lbl" xml:lang="en-US">Subscription Agreement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SubscriptionAgreementDisclosureTextBlock" xlink:to="onco_SubscriptionAgreementDisclosureTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_lbl" xml:lang="en-US">Schedule of Assumptions Used in Monte-Carlo Model, Which Utilizes Level 3 Inputs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:to="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityNoteDisclosureTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock_lbl" xml:lang="en-US">Convertible Redeemable Preferred Stock and Stockholders&apos; Equity</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:to="us-gaap_StockholdersEquityNoteDisclosureTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueOptionQuantitativeDisclosuresTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueOptionQuantitativeDisclosuresTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueOptionQuantitativeDisclosuresTextBlock_lbl" xml:lang="en-US">Schedule of Fair Value of the Preferred Investment Options</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresTextBlock" xlink:to="us-gaap_FairValueOptionQuantitativeDisclosuresTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_lbl" xml:lang="en-US">Exercise price (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" xml:lang="en-US">Term (years)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl0" xml:lang="en-US">Expected term</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl" xml:lang="en-US">Expected stock price volatility</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl0" xml:lang="en-US">Expected volatility</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" xml:lang="en-US">Risk-free rate of interest</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl0" xml:lang="en-US">Risk-free interest rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfValuationOfTheContingentWarrantLiabilityTableTextBlock" xlink:href="onco-20231231.xsd#onco_ScheduleOfValuationOfTheContingentWarrantLiabilityTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ScheduleOfValuationOfTheContingentWarrantLiabilityTableTextBlock_lbl" xml:lang="en-US">Schedule of Valuation of the Contingent Warrant Liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfValuationOfTheContingentWarrantLiabilityTableTextBlock" xlink:to="onco_ScheduleOfValuationOfTheContingentWarrantLiabilityTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfStockholdersEquityNoteWarrantsOrRightsTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockholdersEquityNoteWarrantsOrRightsTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfStockholdersEquityNoteWarrantsOrRightsTextBlock_lbl" xml:lang="en-US">Schedule of Outstanding Warrants, Excluding Contingent Warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfStockholdersEquityNoteWarrantsOrRightsTextBlock" xlink:to="us-gaap_ScheduleOfStockholdersEquityNoteWarrantsOrRightsTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl" xml:lang="en-US">Weighted Average Remaining Contractual Life, ending</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl0" xml:lang="en-US">Weighted average period</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" xml:lang="en-US">Number of Shares, Granted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl0" xml:lang="en-US">Stock options granted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl" xml:lang="en-US">Weighted Average Exercise Price, Granted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl" xml:lang="en-US">Weighted Average Exercise Price, Exercised</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl" xml:lang="en-US">Number of Shares, Cancelled</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl0" xml:lang="en-US">Number of Shares, Forfeited / cancelled</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl1" xml:lang="en-US">Stock options forfeited</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_lbl1"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_lbl" xml:lang="en-US">Weighted Average Exercise Price, Cancelled</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_lbl" xml:lang="en-US">Number of Shares, Warrants vested and exercisable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_lbl" xml:lang="en-US">Weighted Average Exercise Price, Warrants vested and exercisable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_lbl" xml:lang="en-US">Weighted Average Remaining Contractual Life, Warrants vested and exercisable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_lbl" xml:lang="en-US">Schedule of Stock Options</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:to="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueGranted" xlink:href="onco-20231231.xsd#onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueGranted"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueGranted_lbl" xml:lang="en-US">Total Intrinsic Value, Granted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueGranted" xlink:to="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueGranted_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_lbl" xml:lang="en-US">Weighted Average Exercise Price, Forfeited / cancelled</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueForfeitedCancelled" xlink:href="onco-20231231.xsd#onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueForfeitedCancelled"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueForfeitedCancelled_lbl" xml:lang="en-US">Total Intrinsic Value, Forfeited / cancelled</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueForfeitedCancelled" xlink:to="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueForfeitedCancelled_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_lbl" xml:lang="en-US">Total Intrinsic Value, Exercised</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_lbl" xml:lang="en-US">Number of Shares, Options vested and exercisable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_lbl" xml:lang="en-US">Weighted Average Exercise Price, Options vested and exercisable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue_lbl" xml:lang="en-US">Total Intrinsic Value, Options vested and exercisable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_lbl" xml:lang="en-US">Weighted Average Remaining Contractual Life, Options vested and exercisable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfFairValueOfOptionsGrantedIn2023And2022TableTextBlock" xlink:href="onco-20231231.xsd#onco_ScheduleOfFairValueOfOptionsGrantedIn2023And2022TableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ScheduleOfFairValueOfOptionsGrantedIn2023And2022TableTextBlock_lbl" xml:lang="en-US">Schedule of Fair Value of Options Granted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfFairValueOfOptionsGrantedIn2023And2022TableTextBlock" xlink:to="onco_ScheduleOfFairValueOfOptionsGrantedIn2023And2022TableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfNonvestedRestrictedStockUnitsActivityTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfNonvestedRestrictedStockUnitsActivityTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfNonvestedRestrictedStockUnitsActivityTableTextBlock_lbl" xml:lang="en-US">Schedule of Unvested Restricted Stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfNonvestedRestrictedStockUnitsActivityTableTextBlock" xlink:to="us-gaap_ScheduleOfNonvestedRestrictedStockUnitsActivityTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_lbl" xml:lang="en-US">Number of Shares, Granted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xml:lang="en-US">Weighted	Average Grant Date Fair Value, Granted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_lbl" xml:lang="en-US">Weighted	Average Grant Date Fair Value, Forfeited / cancelled</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_lbl" xml:lang="en-US">Weighted	Average Grant Date Fair Value, Vested</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock_lbl" xml:lang="en-US">Schedule of Stock-Based Compensation Expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:to="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xml:lang="en-US">Total stock-based compensation expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllocatedShareBasedCompensationExpense" xlink:to="us-gaap_AllocatedShareBasedCompensationExpense_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingenciesDisclosureTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_lbl" xml:lang="en-US">Commitments and Contingencies</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:to="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsDisclosureTextBlock"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:to="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsNetAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsNetAbstract"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsNetAbstract" xlink:to="us-gaap_DeferredTaxAssetsNetAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:to="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets_lbl" xml:lang="en-US">Intangibles</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch_lbl" xml:lang="en-US">Capitalized research and development</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch" xlink:to="us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits" xlink:to="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsOther"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsOther" xlink:to="us-gaap_DeferredTaxAssetsOther_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities_lbl" xml:lang="en-US">Accrued compensation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities" xlink:to="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_LicenseAgreement" xlink:href="onco-20231231.xsd#onco_LicenseAgreement"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_LicenseAgreement_lbl" xml:lang="en-US">License agreement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_LicenseAgreement" xlink:to="onco_LicenseAgreement_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther_lbl" xml:lang="en-US">Other accrued expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther" xlink:to="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsGross"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="us-gaap_DeferredTaxAssetsGross_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsNet" xlink:to="us-gaap_DeferredTaxAssetsNet_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesNetAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesNetAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DeferredTaxLiabilitiesNetAbstract_lbl" xml:lang="en-US">Deferred tax liabilities:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxLiabilitiesNetAbstract" xlink:to="us-gaap_DeferredTaxLiabilitiesNetAbstract_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_lbl" xml:lang="en-US">Schedule of Income Taxes Differs from the Statutory Federal Rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:to="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_lbl" xml:lang="en-US">Expected income tax benefit at Federal statutory tax rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:to="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_lbl" xml:lang="en-US">State and local taxes, net of Federal tax benefit</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:to="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:to="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:to="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_lbl0" xml:lang="en-US">Foreign NOLs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:to="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost" xlink:to="us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_IncomeTaxReconciliationNondeductibleExpenseDerivativeLiability" xlink:href="onco-20231231.xsd#onco_IncomeTaxReconciliationNondeductibleExpenseDerivativeLiability"/>
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    <loc xlink:type="locator" xlink:label="onco_IncomeTaxReconciliationNondeductibleExpenseOfficersCompensation" xlink:href="onco-20231231.xsd#onco_IncomeTaxReconciliationNondeductibleExpenseOfficersCompensation"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationOtherReconcilingItems" xlink:to="us-gaap_IncomeTaxReconciliationOtherReconcilingItems_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationOtherAdjustments" xlink:to="us-gaap_IncomeTaxReconciliationOtherAdjustments_lbl"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_lbl" xml:lang="en-US">Change in valuation allowance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:to="us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_lbl" xml:lang="en-US">Schedule of Unrecognized Tax Benefits</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock" xlink:to="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_lbl" xml:lang="en-US">Increases related to prior year tax positions</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:to="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_lbl" xml:lang="en-US">Increases related to current year tax positions</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:to="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_lbl" xml:lang="en-US">Retirement Plans</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xlink:to="us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock_lbl" xml:lang="en-US">Schedule of Benefit Obligation and the Net Periodic Benefit Cost</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock" xlink:to="us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_lbl" xml:lang="en-US">Discount rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate_lbl" xml:lang="en-US">Expected long-term rate of return on plan assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease_lbl" xml:lang="en-US">Rate of compensation increase</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTextBlock_lbl" xml:lang="en-US">Schedule of Accompanying Consolidated Balance Sheet</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTextBlock" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanServiceCost" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanServiceCost_lbl" xml:lang="en-US">Service cost</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanServiceCost" xlink:to="us-gaap_DefinedBenefitPlanServiceCost_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DefinedBenefitPlanServiceCost_lbl0" xml:lang="en-US">Services payments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanServiceCost" xlink:to="us-gaap_DefinedBenefitPlanServiceCost_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanInterestCost" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanInterestCost_lbl" xml:lang="en-US">Interest cost</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanInterestCost" xlink:to="us-gaap_DefinedBenefitPlanInterestCost_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock_lbl" xml:lang="en-US">Schedule of Accumulated Comprehensive Loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock" xlink:to="us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPortionAttributableToParent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPortionAttributableToParent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPortionAttributableToParent_lbl" xml:lang="en-US">Net loss (gain)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPortionAttributableToParent" xlink:to="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPortionAttributableToParent_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AmortizationOfNetGain" xlink:href="onco-20231231.xsd#onco_AmortizationOfNetGain"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AmortizationOfNetGain_lbl" xml:lang="en-US">Amortization of net gain</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AmortizationOfNetGain" xlink:to="onco_AmortizationOfNetGain_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_EffectOfSettlement" xlink:href="onco-20231231.xsd#onco_EffectOfSettlement"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_EffectOfSettlement_lbl" xml:lang="en-US">Effect of settlement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_EffectOfSettlement" xlink:to="onco_EffectOfSettlement_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax_lbl" xml:lang="en-US">Other adjustments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetOfTax_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RegulatedAndUnregulatedOperatingRevenue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RegulatedAndUnregulatedOperatingRevenue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RegulatedAndUnregulatedOperatingRevenue_lbl" xml:lang="en-US">Total recorded during the period</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RegulatedAndUnregulatedOperatingRevenue" xlink:to="us-gaap_RegulatedAndUnregulatedOperatingRevenue_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfAccompanyingConsolidatedBalanceSheetTableTextBlock" xlink:href="onco-20231231.xsd#onco_ScheduleOfAccompanyingConsolidatedBalanceSheetTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ScheduleOfAccompanyingConsolidatedBalanceSheetTableTextBlock_lbl" xml:lang="en-US">Schedule of Accompanying Consolidated Balance Sheet</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfAccompanyingConsolidatedBalanceSheetTableTextBlock" xlink:to="onco_ScheduleOfAccompanyingConsolidatedBalanceSheetTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation_lbl" xml:lang="en-US">Projected benefit obligation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation" xlink:to="us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation_lbl0" xml:lang="en-US">Projected benefit obligation as of December 31, 2023</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation" xlink:to="us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_lbl" xml:lang="en-US">Fair value of plan assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_lbl"/>
    <loc xlink:type="locator" xlink:label="srt_ScheduleOfCondensedFinancialStatementsTableTextBlock" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfCondensedFinancialStatementsTableTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_ScheduleOfCondensedFinancialStatementsTableTextBlock_lbl" xml:lang="en-US">Schedule of the Beginning and Ending Balances of the Accumulated Benefit Obligation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTableTextBlock" xlink:to="srt_ScheduleOfCondensedFinancialStatementsTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanActuarialGainLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanActuarialGainLoss_lbl" xml:lang="en-US">Actuarial (gain) loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanActuarialGainLoss" xlink:to="us-gaap_DefinedBenefitPlanActuarialGainLoss_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_DefinedBenefitPlanBenefitObligationOrdinaryContributionsPaidByEmployees" xlink:href="onco-20231231.xsd#onco_DefinedBenefitPlanBenefitObligationOrdinaryContributionsPaidByEmployees"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_DefinedBenefitPlanBenefitObligationOrdinaryContributionsPaidByEmployees_lbl" xml:lang="en-US">Ordinary contributions paid by employees</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DefinedBenefitPlanBenefitObligationOrdinaryContributionsPaidByEmployees" xlink:to="onco_DefinedBenefitPlanBenefitObligationOrdinaryContributionsPaidByEmployees_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_lbl" xml:lang="en-US">Contributions paid by plan participants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationPaymentForSettlement" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligationPaymentForSettlement"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationPaymentForSettlement_lbl" xml:lang="en-US">Settlements</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanBenefitObligationPaymentForSettlement" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligationPaymentForSettlement_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanOtherChanges" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanOtherChanges"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanOtherChanges_lbl" xml:lang="en-US">Actuarial (gain)/loss due to assumption changes</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanOtherChanges" xlink:to="us-gaap_DefinedBenefitPlanOtherChanges_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationPeriodIncreaseDecrease" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligationPeriodIncreaseDecrease"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationPeriodIncreaseDecrease_lbl" xml:lang="en-US">Actuarial (gain)/loss due to plan experience</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanBenefitObligationPeriodIncreaseDecrease" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligationPeriodIncreaseDecrease_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_lbl" xml:lang="en-US">Actual return on plan assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DefinedBenefitPlanPlanAssetsOrdinaryContributionsPaidByEmployees" xlink:to="onco_DefinedBenefitPlanPlanAssetsOrdinaryContributionsPaidByEmployees_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant" xlink:to="us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesTableTextBlock"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesTableTextBlock" xlink:to="us-gaap_ScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesTableTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_lbl" xml:lang="en-US">2024</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_lbl" xml:lang="en-US">2025</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_lbl" xml:lang="en-US">2026</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_lbl" xml:lang="en-US">2027</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_lbl" xml:lang="en-US">2028</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_lbl" xml:lang="en-US">Thereafter</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SubsequentEventsTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventsTextBlock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SubsequentEventsTextBlock_lbl" xml:lang="en-US">Subsequent Events</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventsTextBlock" xlink:to="us-gaap_SubsequentEventsTextBlock_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPeriodIncreaseDecrease" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPeriodIncreaseDecrease"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPeriodIncreaseDecrease_lbl" xml:lang="en-US">Change in fair value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPeriodIncreaseDecrease" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPeriodIncreaseDecrease_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AmortizationOfIntangibleAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_AmortizationOfIntangibleAssets_lbl" xml:lang="en-US">Amortization</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AmortizationOfIntangibleAssets" xlink:to="us-gaap_AmortizationOfIntangibleAssets_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AmortizationOfIntangibleAssets_lbl0" xml:lang="en-US">Amortization expense related to intangible assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AmortizationOfIntangibleAssets" xlink:to="us-gaap_AmortizationOfIntangibleAssets_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_lbl" xml:lang="en-US">Accounts payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpenses" xlink:href="onco-20231231.xsd#onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpenses"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpenses_lbl" xml:lang="en-US">Accrued expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpenses" xlink:to="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpenses_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation_lbl" xml:lang="en-US">Operating lease liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_lbl" xml:lang="en-US">Deferred tax liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPensionBenefitObligation" xlink:href="onco-20231231.xsd#onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPensionBenefitObligation"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPensionBenefitObligation_lbl" xml:lang="en-US">Pension benefit obligation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPensionBenefitObligation" xlink:to="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPensionBenefitObligation_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNotePayable" xlink:href="onco-20231231.xsd#onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNotePayable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNotePayable_lbl" xml:lang="en-US">Note payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNotePayable" xlink:to="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNotePayable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue_lbl" xml:lang="en-US">Less non-controlling interest</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue" xlink:to="us-gaap_BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_lbl" xml:lang="en-US">Number of Shares, Forfeited / cancelled</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_lbl" xml:lang="en-US">Number of Shares, Vested</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance_lbl" xml:lang="en-US">Valuation allowance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsValuationAllowance" xlink:to="us-gaap_DeferredTaxAssetsValuationAllowance_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xlink:to="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_lbl" xml:lang="en-US">Fixed assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:to="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesOther"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DeferredTaxLiabilitiesOther_lbl" xml:lang="en-US">Other</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxLiabilitiesOther" xlink:to="us-gaap_DeferredTaxLiabilitiesOther_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DeferredIncomeTaxLiabilities_lbl" xml:lang="en-US">Total deferred tax liabilities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxLiabilities" xlink:to="us-gaap_DeferredIncomeTaxLiabilities_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DeferredTaxLiabilities_lbl" xml:lang="en-US">Net deferred tax liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxLiabilities" xlink:to="us-gaap_DeferredTaxLiabilities_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationTaxCreditsResearch" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsResearch"/>
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    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_lbl" xml:lang="en-US">Expected return on plan assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_lbl" xml:lang="en-US">Amortization of net (gain)/loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses" xlink:to="us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_lbl" xml:lang="en-US">Settlements (gain)/loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1" xlink:to="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_lbl" xml:lang="en-US">Benefits paid</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_lbl" xml:lang="en-US">Benefits paid</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid" xlink:to="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanSettlementsPlanAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanSettlementsPlanAssets"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:label="us-gaap_DefinedBenefitPlanSettlementsPlanAssets_lbl" xml:lang="en-US">Settlements</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanSettlementsPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanSettlementsPlanAssets_lbl"/>
    <loc xlink:type="locator" xlink:label="country_US" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="country_US_lbl" xml:lang="en-US">United States [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="country_US" xlink:to="country_US_lbl"/>
    <loc xlink:type="locator" xlink:label="country_CH" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_CH"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="country_CH_lbl" xml:lang="en-US">Switzerland [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="country_CH" xlink:to="country_CH_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="country_CH_lbl0" xml:lang="en-US">Zurich Switzerland [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="country_CH" xlink:to="country_CH_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel1Member" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueInputsLevel1Member_lbl" xml:lang="en-US">Level 1 [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueInputsLevel1Member" xlink:to="us-gaap_FairValueInputsLevel1Member_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel2Member" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueInputsLevel2Member_lbl" xml:lang="en-US">Level 2 [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueInputsLevel2Member" xlink:to="us-gaap_FairValueInputsLevel2Member_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel3Member" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FairValueInputsLevel3Member_lbl" xml:lang="en-US">Level 3 [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueInputsLevel3Member" xlink:to="us-gaap_FairValueInputsLevel3Member_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_FairValueInputsLevel3Member_lbl0" xml:lang="en-US">Level 3 Inputs [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueInputsLevel3Member" xlink:to="us-gaap_FairValueInputsLevel3Member_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_SubscriptionAgreementLiabilityMember" xlink:href="onco-20231231.xsd#onco_SubscriptionAgreementLiabilityMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SubscriptionAgreementLiabilityMember_lbl" xml:lang="en-US">Subscription Agreement Liability [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SubscriptionAgreementLiabilityMember" xlink:to="onco_SubscriptionAgreementLiabilityMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ContingentWarrantLiabilityMember" xlink:href="onco-20231231.xsd#onco_ContingentWarrantLiabilityMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ContingentWarrantLiabilityMember_lbl" xml:lang="en-US">Contingent Warrant Liability [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ContingentWarrantLiabilityMember" xlink:to="onco_ContingentWarrantLiabilityMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StockOptionsMember" xlink:href="onco-20231231.xsd#onco_StockOptionsMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StockOptionsMember_lbl" xml:lang="en-US">Stock options [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockOptionsMember" xlink:to="onco_StockOptionsMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_WarrantMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WarrantMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_WarrantMember_lbl" xml:lang="en-US">Warrants [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_WarrantMember" xlink:to="us-gaap_WarrantMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_WarrantMember_lbl0" xml:lang="en-US">Warrant [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_WarrantMember" xlink:to="us-gaap_WarrantMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RestrictedStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RestrictedStockMember_lbl" xml:lang="en-US">Unvested restricted stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestrictedStockMember" xlink:to="us-gaap_RestrictedStockMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_RestrictedStockMember_lbl0" xml:lang="en-US">Restricted Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestrictedStockMember" xlink:to="us-gaap_RestrictedStockMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_CommonStockIssuableUponConversionOfSeriesAPreferredStockMember" xlink:href="onco-20231231.xsd#onco_CommonStockIssuableUponConversionOfSeriesAPreferredStockMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_CommonStockIssuableUponConversionOfSeriesAPreferredStockMember_lbl" xml:lang="en-US">Common stock issuable upon conversion of Series A preferred stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CommonStockIssuableUponConversionOfSeriesAPreferredStockMember" xlink:to="onco_CommonStockIssuableUponConversionOfSeriesAPreferredStockMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TradeNamesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TradeNamesMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_TradeNamesMember_lbl" xml:lang="en-US">Trade name [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TradeNamesMember" xlink:to="us-gaap_TradeNamesMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_TradeNamesMember_lbl0" xml:lang="en-US">Trade Names [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TradeNamesMember" xlink:to="us-gaap_TradeNamesMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DevelopedTechnologyRightsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DevelopedTechnologyRightsMember_lbl" xml:lang="en-US">Product rights for developed technology [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DevelopedTechnologyRightsMember" xlink:to="us-gaap_DevelopedTechnologyRightsMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DevelopedTechnologyRightsMember_lbl0" xml:lang="en-US">Product Rights Intangible Asset [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DevelopedTechnologyRightsMember" xlink:to="us-gaap_DevelopedTechnologyRightsMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/netLabel" xlink:label="us-gaap_DevelopedTechnologyRightsMember_lbl1" xml:lang="en-US">Product Rights Developed Technology [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DevelopedTechnologyRightsMember" xlink:to="us-gaap_DevelopedTechnologyRightsMember_lbl1"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CustomerRelationshipsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CustomerRelationshipsMember_lbl" xml:lang="en-US">Customer relationships [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CustomerRelationshipsMember" xlink:to="us-gaap_CustomerRelationshipsMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_CustomerRelationshipsMember_lbl0" xml:lang="en-US">Customer Relationships [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CustomerRelationshipsMember" xlink:to="us-gaap_CustomerRelationshipsMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_AggregateConsiderationTransferredMember" xlink:href="onco-20231231.xsd#onco_AggregateConsiderationTransferredMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AggregateConsiderationTransferredMember_lbl" xml:lang="en-US">Aggregate Consideration Transferred [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateConsiderationTransferredMember" xlink:to="onco_AggregateConsiderationTransferredMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_FairValueConsiderationTransferredMember" xlink:href="onco-20231231.xsd#onco_FairValueConsiderationTransferredMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_FairValueConsiderationTransferredMember_lbl" xml:lang="en-US">Fair Value Consideration Transferred [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_FairValueConsiderationTransferredMember" xlink:to="onco_FairValueConsiderationTransferredMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AssetsRecognizedMember" xlink:href="onco-20231231.xsd#onco_AssetsRecognizedMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AssetsRecognizedMember_lbl" xml:lang="en-US">Assets Recognized	[Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AssetsRecognizedMember" xlink:to="onco_AssetsRecognizedMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_MeasurementInputStockPriceMember" xlink:href="onco-20231231.xsd#onco_MeasurementInputStockPriceMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_MeasurementInputStockPriceMember_lbl" xml:lang="en-US">Stock price [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_MeasurementInputStockPriceMember" xlink:to="onco_MeasurementInputStockPriceMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MeasurementInputExpectedTermMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputExpectedTermMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_MeasurementInputExpectedTermMember_lbl" xml:lang="en-US">Term (years) [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputExpectedTermMember" xlink:to="us-gaap_MeasurementInputExpectedTermMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_MeasurementInputExpectedTermMember_lbl0" xml:lang="en-US">Term [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputExpectedTermMember" xlink:to="us-gaap_MeasurementInputExpectedTermMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/netLabel" xlink:label="us-gaap_MeasurementInputExpectedTermMember_lbl1" xml:lang="en-US">Measurement Input, Expected Term [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputExpectedTermMember" xlink:to="us-gaap_MeasurementInputExpectedTermMember_lbl1"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MeasurementInputPriceVolatilityMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputPriceVolatilityMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_MeasurementInputPriceVolatilityMember_lbl" xml:lang="en-US">Expected stock price volatility	[Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputPriceVolatilityMember" xlink:to="us-gaap_MeasurementInputPriceVolatilityMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_MeasurementInputPriceVolatilityMember_lbl0" xml:lang="en-US">Measurement Input, Price Volatility [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputPriceVolatilityMember" xlink:to="us-gaap_MeasurementInputPriceVolatilityMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MeasurementInputRiskFreeInterestRateMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputRiskFreeInterestRateMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_MeasurementInputRiskFreeInterestRateMember_lbl" xml:lang="en-US">Risk-free rate of interest [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputRiskFreeInterestRateMember" xlink:to="us-gaap_MeasurementInputRiskFreeInterestRateMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_MeasurementInputRiskFreeInterestRateMember_lbl0" xml:lang="en-US">Risk-free Rate of Interest [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputRiskFreeInterestRateMember" xlink:to="us-gaap_MeasurementInputRiskFreeInterestRateMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/netLabel" xlink:label="us-gaap_MeasurementInputRiskFreeInterestRateMember_lbl1" xml:lang="en-US">Measurement Input, Risk Free Interest Rate [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputRiskFreeInterestRateMember" xlink:to="us-gaap_MeasurementInputRiskFreeInterestRateMember_lbl1"/>
    <loc xlink:type="locator" xlink:label="srt_MinimumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_MinimumMember_lbl" xml:lang="en-US">Minimum [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MinimumMember" xlink:to="srt_MinimumMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="srt_MinimumMember_lbl0" xml:lang="en-US">Property and Equipment [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MinimumMember" xlink:to="srt_MinimumMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockOptionMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockOptionMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockOptionMember_lbl" xml:lang="en-US">Stock Option [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockOptionMember" xlink:to="us-gaap_StockOptionMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_StockOptionMember_lbl0" xml:lang="en-US">Stock Options [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockOptionMember" xlink:to="us-gaap_StockOptionMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/netLabel" xlink:label="us-gaap_StockOptionMember_lbl1" xml:lang="en-US">Equity Option [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockOptionMember" xlink:to="us-gaap_StockOptionMember_lbl1"/>
    <loc xlink:type="locator" xlink:label="srt_MaximumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_MaximumMember_lbl" xml:lang="en-US">Maximum [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MaximumMember" xlink:to="srt_MaximumMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_BusinessAcquisitionMember" xlink:href="onco-20231231.xsd#onco_BusinessAcquisitionMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_BusinessAcquisitionMember_lbl" xml:lang="en-US">Business Acquisition [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessAcquisitionMember" xlink:to="onco_BusinessAcquisitionMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ProteomedixMember" xlink:href="onco-20231231.xsd#onco_ProteomedixMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ProteomedixMember_lbl" xml:lang="en-US">Proteomedix [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ProteomedixMember" xlink:to="onco_ProteomedixMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PMXTransactionMember" xlink:href="onco-20231231.xsd#onco_PMXTransactionMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PMXTransactionMember_lbl" xml:lang="en-US">PMX Transaction [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PMXTransactionMember" xlink:to="onco_PMXTransactionMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MeasurementInputExercisePriceMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputExercisePriceMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_MeasurementInputExercisePriceMember_lbl" xml:lang="en-US">Exercise Price [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputExercisePriceMember" xlink:to="us-gaap_MeasurementInputExercisePriceMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MeasurementInputOptionVolatilityMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputOptionVolatilityMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_MeasurementInputOptionVolatilityMember_lbl" xml:lang="en-US">Expected Stock Price Volatility [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputOptionVolatilityMember" xlink:to="us-gaap_MeasurementInputOptionVolatilityMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_OriginalMember" xlink:href="onco-20231231.xsd#onco_OriginalMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_OriginalMember_lbl" xml:lang="en-US">Original [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_OriginalMember" xlink:to="onco_OriginalMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ExchangedMember" xlink:href="onco-20231231.xsd#onco_ExchangedMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ExchangedMember_lbl" xml:lang="en-US">Exchanged [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ExchangedMember" xlink:to="onco_ExchangedMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PrivatePlacementMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrivatePlacementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PrivatePlacementMember_lbl" xml:lang="en-US">Private Placement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrivatePlacementMember" xlink:to="us-gaap_PrivatePlacementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpensesMember_lbl" xml:lang="en-US">Selling, general and administrative [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpensesMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ResearchAndDevelopmentMember" xlink:href="onco-20231231.xsd#onco_ResearchAndDevelopmentMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ResearchAndDevelopmentMember_lbl" xml:lang="en-US">Research and development [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ResearchAndDevelopmentMember" xlink:to="onco_ResearchAndDevelopmentMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AccumulatedBenefitObligationMember" xlink:href="onco-20231231.xsd#onco_AccumulatedBenefitObligationMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AccumulatedBenefitObligationMember_lbl" xml:lang="en-US">Accumulated Benefit Obligation [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AccumulatedBenefitObligationMember" xlink:to="onco_AccumulatedBenefitObligationMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PlanAssetsMember" xlink:href="onco-20231231.xsd#onco_PlanAssetsMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PlanAssetsMember_lbl" xml:lang="en-US">Plan Assets [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PlanAssetsMember" xlink:to="onco_PlanAssetsMember_lbl"/>
    <loc xlink:type="locator" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_lbl" xml:lang="en-US">Investment, Name [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="srt_OwnershipAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_OwnershipAxis_lbl" xml:lang="en-US">Ownership [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_OwnershipAxis" xlink:to="srt_OwnershipAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SubsequentEventTypeAxis_lbl" xml:lang="en-US">Subsequent Event Type [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xml:lang="en-US">Long-Lived Tangible Asset [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtInstrumentAxis_lbl" xml:lang="en-US">Debt Instrument [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RelatedPartyTransactionAxis_lbl" xml:lang="en-US">Related Party Transaction [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EquitySecuritiesByIndustryAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EquitySecuritiesByIndustryAxis_lbl" xml:lang="en-US">Industry Sector [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EquitySecuritiesByIndustryAxis" xlink:to="us-gaap_EquitySecuritiesByIndustryAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="srt_StatementScenarioAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementScenarioAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_StatementScenarioAxis_lbl" xml:lang="en-US">Scenario [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_StatementScenarioAxis" xlink:to="srt_StatementScenarioAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PlanNameAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PlanNameAxis_lbl" xml:lang="en-US">Plan Name [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="srt_TitleOfIndividualAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_TitleOfIndividualAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_TitleOfIndividualAxis_lbl" xml:lang="en-US">Title of Individual [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_lbl" xml:lang="en-US">Research and Development Arrangement, Contract to Perform for Others, Type [Axis]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" xlink:to="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EquityMethodInvestmentOwnershipPercentage_lbl" xml:lang="en-US">Equity interest ownership percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:to="us-gaap_EquityMethodInvestmentOwnershipPercentage_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MinorityInterestOwnershipPercentageByParent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_MinorityInterestOwnershipPercentageByParent_lbl" xml:lang="en-US">Subsidiary owned, percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MinorityInterestOwnershipPercentageByParent" xlink:to="us-gaap_MinorityInterestOwnershipPercentageByParent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ReclassificationsOfTemporaryToPermanentEquity" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReclassificationsOfTemporaryToPermanentEquity"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ReclassificationsOfTemporaryToPermanentEquity_lbl" xml:lang="en-US">Reclassifications cash flow activity</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ReclassificationsOfTemporaryToPermanentEquity" xlink:to="us-gaap_ReclassificationsOfTemporaryToPermanentEquity_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_InitialPublicOfferingShares" xlink:href="onco-20231231.xsd#onco_InitialPublicOfferingShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_InitialPublicOfferingShares_lbl" xml:lang="en-US">Common stock (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_InitialPublicOfferingShares" xlink:to="onco_InitialPublicOfferingShares_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PublicOfPerShare" xlink:href="onco-20231231.xsd#onco_PublicOfPerShare"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PublicOfPerShare_lbl" xml:lang="en-US">Public of per share (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PublicOfPerShare" xlink:to="onco_PublicOfPerShare_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ConvertiblePreferredStockSharesReservedForFutureIssuance" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertiblePreferredStockSharesReservedForFutureIssuance"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ConvertiblePreferredStockSharesReservedForFutureIssuance_lbl" xml:lang="en-US">Convertible preferred stock shares (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConvertiblePreferredStockSharesReservedForFutureIssuance" xlink:to="us-gaap_ConvertiblePreferredStockSharesReservedForFutureIssuance_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfPrivatePlacement" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceOfPrivatePlacement"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_lbl" xml:lang="en-US">Net proceeds</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceOfPrivatePlacement" xlink:to="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_lbl0" xml:lang="en-US">Private placement were approximatel (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceOfPrivatePlacement" xlink:to="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromSaleOfOtherInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromSaleOfOtherInvestments"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromSaleOfOtherInvestments_lbl" xml:lang="en-US">Proceeds from preferred investment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromSaleOfOtherInvestments" xlink:to="us-gaap_ProceedsFromSaleOfOtherInvestments_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_WorkingCapitalDeficit" xlink:href="onco-20231231.xsd#onco_WorkingCapitalDeficit"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_WorkingCapitalDeficit_lbl" xml:lang="en-US">Working capital deficit</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WorkingCapitalDeficit" xlink:to="onco_WorkingCapitalDeficit_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RetainedEarningsAppropriated" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsAppropriated"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RetainedEarningsAppropriated_lbl" xml:lang="en-US">Accumulated deficit</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetainedEarningsAppropriated" xlink:to="us-gaap_RetainedEarningsAppropriated_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NumberOfOperatingSegments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfOperatingSegments"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NumberOfOperatingSegments_lbl" xml:lang="en-US">Operating segment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NumberOfOperatingSegments" xlink:to="us-gaap_NumberOfOperatingSegments_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InventoryValuationReserves" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryValuationReserves"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_InventoryValuationReserves_lbl" xml:lang="en-US">Inventory reserve</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryValuationReserves" xlink:to="us-gaap_InventoryValuationReserves_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl" xml:lang="en-US">Useful lives</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:to="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl0" xml:lang="en-US">Estimated useful lives</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:to="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_Depreciation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Depreciation"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_Depreciation_lbl" xml:lang="en-US">Depreciation expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Depreciation" xlink:to="us-gaap_Depreciation_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_GoodwillImpairmentLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_GoodwillImpairmentLoss_lbl" xml:lang="en-US">Impairment loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillImpairmentLoss" xlink:to="us-gaap_GoodwillImpairmentLoss_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf_lbl" xml:lang="en-US">Impairment loss of long lived assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf" xlink:to="us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RecognitionOfDeferredRevenue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RecognitionOfDeferredRevenue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RecognitionOfDeferredRevenue_lbl" xml:lang="en-US">Revenue</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RecognitionOfDeferredRevenue" xlink:to="us-gaap_RecognitionOfDeferredRevenue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccountsReceivableNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableNet"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccountsReceivableNet_lbl" xml:lang="en-US">Accounts receivable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsReceivableNet" xlink:to="us-gaap_AccountsReceivableNet_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherCostOfOperatingRevenue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCostOfOperatingRevenue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherCostOfOperatingRevenue_lbl" xml:lang="en-US">Cost of revenue</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherCostOfOperatingRevenue" xlink:to="us-gaap_OtherCostOfOperatingRevenue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherSellingGeneralAndAdministrativeExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherSellingGeneralAndAdministrativeExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherSellingGeneralAndAdministrativeExpense_lbl" xml:lang="en-US">Selling, general, and administrative expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherSellingGeneralAndAdministrativeExpense" xlink:to="us-gaap_OtherSellingGeneralAndAdministrativeExpense_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OtherSellingGeneralAndAdministrativeExpense_lbl0" xml:lang="en-US">Selling, general and administrative expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherSellingGeneralAndAdministrativeExpense" xlink:to="us-gaap_OtherSellingGeneralAndAdministrativeExpense_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AssetImpairmentCharges" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetImpairmentCharges"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AssetImpairmentCharges_lbl" xml:lang="en-US">Impairment charge</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetImpairmentCharges" xlink:to="us-gaap_AssetImpairmentCharges_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_lbl" xml:lang="en-US">Weighted-average remaining amortization period</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:to="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IndefiniteLivedTradeNames" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedTradeNames"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IndefiniteLivedTradeNames_lbl" xml:lang="en-US">Indefinite life intangible assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IndefiniteLivedTradeNames" xlink:to="us-gaap_IndefiniteLivedTradeNames_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_lbl" xml:lang="en-US">Consideration amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts" xlink:to="us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionDescriptionOfAcquiredEntity" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionDescriptionOfAcquiredEntity"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_BusinessAcquisitionDescriptionOfAcquiredEntity_lbl" xml:lang="en-US">Business acquisition, description</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionDescriptionOfAcquiredEntity" xlink:to="us-gaap_BusinessAcquisitionDescriptionOfAcquiredEntity_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_RoyaltySalesPercentage" xlink:href="onco-20231231.xsd#onco_RoyaltySalesPercentage"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_RoyaltySalesPercentage_lbl" xml:lang="en-US">Royalty sales percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltySalesPercentage" xlink:to="onco_RoyaltySalesPercentage_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_SalesPaymentsAmount" xlink:href="onco-20231231.xsd#onco_SalesPaymentsAmount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SalesPaymentsAmount_lbl" xml:lang="en-US">Sales payments amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SalesPaymentsAmount" xlink:to="onco_SalesPaymentsAmount_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionProFormaInformationDescription" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionProFormaInformationDescription"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_BusinessAcquisitionProFormaInformationDescription_lbl" xml:lang="en-US">Business acquisition, description</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionProFormaInformationDescription" xlink:to="us-gaap_BusinessAcquisitionProFormaInformationDescription_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AggregatePurchaseShares" xlink:href="onco-20231231.xsd#onco_AggregatePurchaseShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AggregatePurchaseShares_lbl" xml:lang="en-US">Aggregate shares (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregatePurchaseShares" xlink:to="onco_AggregatePurchaseShares_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="onco_AggregatePurchaseShares_lbl0" xml:lang="en-US">Purchase of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregatePurchaseShares" xlink:to="onco_AggregatePurchaseShares_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_BusinessTransactionYeare" xlink:href="onco-20231231.xsd#onco_BusinessTransactionYeare"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_BusinessTransactionYeare_lbl" xml:lang="en-US">Business transaction years</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessTransactionYeare" xlink:to="onco_BusinessTransactionYeare_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl" xml:lang="en-US">Estimated using discount percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:to="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl0" xml:lang="en-US">Accrue interest rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:to="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/netLabel" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl1" xml:lang="en-US">Debenture interest rate percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:to="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl1"/>
    <loc xlink:type="locator" xlink:label="onco_InventoryFairValue" xlink:href="onco-20231231.xsd#onco_InventoryFairValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_InventoryFairValue_lbl" xml:lang="en-US">Inventory fair value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_InventoryFairValue" xlink:to="onco_InventoryFairValue_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ImpairmentRate" xlink:href="onco-20231231.xsd#onco_ImpairmentRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ImpairmentRate_lbl" xml:lang="en-US">Impairment rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ImpairmentRate" xlink:to="onco_ImpairmentRate_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCosts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCosts"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCosts_lbl" xml:lang="en-US">Cash payment amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCosts" xlink:to="us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCosts_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_InitialPaymentAmount" xlink:href="onco-20231231.xsd#onco_InitialPaymentAmount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_InitialPaymentAmount_lbl" xml:lang="en-US">Initial payment amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_InitialPaymentAmount" xlink:to="onco_InitialPaymentAmount_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_Payments" xlink:href="onco-20231231.xsd#onco_Payments"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_Payments_lbl" xml:lang="en-US">Company payments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_Payments" xlink:to="onco_Payments_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_Deposits" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Deposits"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_Deposits_lbl" xml:lang="en-US">Payment as deposit</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Deposits" xlink:to="us-gaap_Deposits_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CashFDICInsuredAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashFDICInsuredAmount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CashFDICInsuredAmount_lbl" xml:lang="en-US">Cash target amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CashFDICInsuredAmount" xlink:to="us-gaap_CashFDICInsuredAmount_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsForFees" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForFees"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PaymentsForFees_lbl" xml:lang="en-US">Initial payment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsForFees" xlink:to="us-gaap_PaymentsForFees_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_PaymentsForFees_lbl0" xml:lang="en-US">Fees under consulting agreement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsForFees" xlink:to="us-gaap_PaymentsForFees_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_VotingInterestPercentage" xlink:href="onco-20231231.xsd#onco_VotingInterestPercentage"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_VotingInterestPercentage_lbl" xml:lang="en-US">Voting interest percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_VotingInterestPercentage" xlink:to="onco_VotingInterestPercentage_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_NumberOfShares" xlink:href="onco-20231231.xsd#onco_NumberOfShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_NumberOfShares_lbl" xml:lang="en-US">Number of shares (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_NumberOfShares" xlink:to="onco_NumberOfShares_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_RoyaltyRate" xlink:href="onco-20231231.xsd#onco_RoyaltyRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_RoyaltyRate_lbl" xml:lang="en-US">Royalty rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltyRate" xlink:to="onco_RoyaltyRate_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_WeightedAverageDiscountRate" xlink:href="onco-20231231.xsd#onco_WeightedAverageDiscountRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_WeightedAverageDiscountRate_lbl" xml:lang="en-US">Discount rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WeightedAverageDiscountRate" xlink:to="onco_WeightedAverageDiscountRate_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_WeightedAverageDiscountRateThereafter" xlink:href="onco-20231231.xsd#onco_WeightedAverageDiscountRateThereafter"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_WeightedAverageDiscountRateThereafter_lbl" xml:lang="en-US">Discount rate thereafter</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WeightedAverageDiscountRateThereafter" xlink:to="onco_WeightedAverageDiscountRateThereafter_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InvestmentOwnedAtCost" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentOwnedAtCost"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_InvestmentOwnedAtCost_lbl" xml:lang="en-US">Related cost</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InvestmentOwnedAtCost" xlink:to="us-gaap_InvestmentOwnedAtCost_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AggregateAgreementAmountInitialAgreement" xlink:href="onco-20231231.xsd#onco_AggregateAgreementAmountInitialAgreement"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AggregateAgreementAmountInitialAgreement_lbl" xml:lang="en-US">Aggregate agreement amount initial agreement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateAgreementAmountInitialAgreement" xlink:to="onco_AggregateAgreementAmountInitialAgreement_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AggregateeAmount" xlink:href="onco-20231231.xsd#onco_AggregateeAmount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AggregateeAmount_lbl" xml:lang="en-US">Aggregate amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateeAmount" xlink:to="onco_AggregateeAmount_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_CostPlusPercentage" xlink:href="onco-20231231.xsd#onco_CostPlusPercentage"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_CostPlusPercentage_lbl" xml:lang="en-US">Cost plus, percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CostPlusPercentage" xlink:to="onco_CostPlusPercentage_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccountsPayableCurrentAndNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableCurrentAndNoncurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccountsPayableCurrentAndNoncurrent_lbl" xml:lang="en-US">Accounts payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableCurrentAndNoncurrent" xlink:to="us-gaap_AccountsPayableCurrentAndNoncurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_lbl" xml:lang="en-US">Accrued expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent" xlink:to="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_CommercialSaleTerm" xlink:href="onco-20231231.xsd#onco_CommercialSaleTerm"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_CommercialSaleTerm_lbl" xml:lang="en-US">Commercial sale term</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CommercialSaleTerm" xlink:to="onco_CommercialSaleTerm_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_RoyaltyNetSalesPercentage" xlink:href="onco-20231231.xsd#onco_RoyaltyNetSalesPercentage"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_RoyaltyNetSalesPercentage_lbl" xml:lang="en-US">Royalty net sales percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltyNetSalesPercentage" xlink:to="onco_RoyaltyNetSalesPercentage_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProductLiabilityContingencyAccrualDiscountRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductLiabilityContingencyAccrualDiscountRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProductLiabilityContingencyAccrualDiscountRate_lbl" xml:lang="en-US">Percentage of product</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProductLiabilityContingencyAccrualDiscountRate" xlink:to="us-gaap_ProductLiabilityContingencyAccrualDiscountRate_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_RoyaltyRates" xlink:href="onco-20231231.xsd#onco_RoyaltyRates"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_RoyaltyRates_lbl" xml:lang="en-US">Royalty rates</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltyRates" xlink:to="onco_RoyaltyRates_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_RevenueRate" xlink:href="onco-20231231.xsd#onco_RevenueRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_RevenueRate_lbl" xml:lang="en-US">Revenue rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RevenueRate" xlink:to="onco_RevenueRate_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FeeIncome" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FeeIncome"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_FeeIncome_lbl" xml:lang="en-US">Option fee</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FeeIncome" xlink:to="us-gaap_FeeIncome_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_FeeIncome_lbl0" xml:lang="en-US">Cash fee</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FeeIncome" xlink:to="us-gaap_FeeIncome_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_AggregateRoyaltiesAmount" xlink:href="onco-20231231.xsd#onco_AggregateRoyaltiesAmount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AggregateRoyaltiesAmount_lbl" xml:lang="en-US">Aggregate payments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateRoyaltiesAmount" xlink:to="onco_AggregateRoyaltiesAmount_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DevelopmentCosts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DevelopmentCosts"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DevelopmentCosts_lbl" xml:lang="en-US">Development milestones costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DevelopmentCosts" xlink:to="us-gaap_DevelopmentCosts_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RoyaltyExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RoyaltyExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RoyaltyExpense_lbl" xml:lang="en-US">Royalty payment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RoyaltyExpense" xlink:to="us-gaap_RoyaltyExpense_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CostOfPropertyRepairsAndMaintenance" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfPropertyRepairsAndMaintenance"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CostOfPropertyRepairsAndMaintenance_lbl" xml:lang="en-US">Maintenance fee</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CostOfPropertyRepairsAndMaintenance" xlink:to="us-gaap_CostOfPropertyRepairsAndMaintenance_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PercentageOfConsiderationReceived" xlink:href="onco-20231231.xsd#onco_PercentageOfConsiderationReceived"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PercentageOfConsiderationReceived_lbl" xml:lang="en-US">Percentage of consideration received</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfConsiderationReceived" xlink:to="onco_PercentageOfConsiderationReceived_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TaxesAndLicenses" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TaxesAndLicenses"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_TaxesAndLicenses_lbl" xml:lang="en-US">License fee</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TaxesAndLicenses" xlink:to="us-gaap_TaxesAndLicenses_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CostMaintenance" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostMaintenance"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CostMaintenance_lbl" xml:lang="en-US">Annual maintenance fee</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CostMaintenance" xlink:to="us-gaap_CostMaintenance_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromLicenseFeesReceived" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromLicenseFeesReceived"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProceedsFromLicenseFeesReceived_lbl" xml:lang="en-US">License fee</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromLicenseFeesReceived" xlink:to="us-gaap_ProceedsFromLicenseFeesReceived_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AmountOfOtherPartyPayments" xlink:href="onco-20231231.xsd#onco_AmountOfOtherPartyPayments"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AmountOfOtherPartyPayments_lbl" xml:lang="en-US">Other party payments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AmountOfOtherPartyPayments" xlink:to="onco_AmountOfOtherPartyPayments_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_RoyaltiesPercentage" xlink:href="onco-20231231.xsd#onco_RoyaltiesPercentage"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_RoyaltiesPercentage_lbl" xml:lang="en-US">Royalties percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltiesPercentage" xlink:to="onco_RoyaltiesPercentage_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFeeAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFeeAmount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtInstrumentFeeAmount_lbl" xml:lang="en-US">Sales-related services fee</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentFeeAmount" xlink:to="us-gaap_DebtInstrumentFeeAmount_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AdministrativeFeesExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdministrativeFeesExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AdministrativeFeesExpense_lbl" xml:lang="en-US">Total amount of fee expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdministrativeFeesExpense" xlink:to="us-gaap_AdministrativeFeesExpense_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LongTermDebtMaturityDate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturityDate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LongTermDebtMaturityDate_lbl" xml:lang="en-US">Maturity term</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtMaturityDate" xlink:to="us-gaap_LongTermDebtMaturityDate_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProfessionalAndContractServicesExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProfessionalAndContractServicesExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProfessionalAndContractServicesExpense_lbl" xml:lang="en-US">Expense related to contract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProfessionalAndContractServicesExpense" xlink:to="us-gaap_ProfessionalAndContractServicesExpense_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_LicensedProductsPlusMilestonePaymentsDescription" xlink:href="onco-20231231.xsd#onco_LicensedProductsPlusMilestonePaymentsDescription"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_LicensedProductsPlusMilestonePaymentsDescription_lbl" xml:lang="en-US">Description of licensed products</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_LicensedProductsPlusMilestonePaymentsDescription" xlink:to="onco_LicensedProductsPlusMilestonePaymentsDescription_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentAnnualPrincipalPayment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAnnualPrincipalPayment"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtInstrumentAnnualPrincipalPayment_lbl" xml:lang="en-US">Principal payment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentAnnualPrincipalPayment" xlink:to="us-gaap_DebtInstrumentAnnualPrincipalPayment_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_DebtInstrumentAnnualPrincipalPayment_lbl0" xml:lang="en-US">Principal amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentAnnualPrincipalPayment" xlink:to="us-gaap_DebtInstrumentAnnualPrincipalPayment_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentMaturityDate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentMaturityDate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtInstrumentMaturityDate_lbl" xml:lang="en-US">Maturity date</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentMaturityDate" xlink:to="us-gaap_DebtInstrumentMaturityDate_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PayableAverageDiscountRatePercentage" xlink:href="onco-20231231.xsd#onco_PayableAverageDiscountRatePercentage"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PayableAverageDiscountRatePercentage_lbl" xml:lang="en-US">Average discount rate, percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PayableAverageDiscountRatePercentage" xlink:to="onco_PayableAverageDiscountRatePercentage_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFaceAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtInstrumentFaceAmount_lbl" xml:lang="en-US">Principal amounts</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentFaceAmount" xlink:to="us-gaap_DebtInstrumentFaceAmount_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InterestExpenseDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseDebt"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_InterestExpenseDebt_lbl" xml:lang="en-US">Interest expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestExpenseDebt" xlink:to="us-gaap_InterestExpenseDebt_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentUnamortizedDiscount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtInstrumentUnamortizedDiscount_lbl" xml:lang="en-US">Unamortized debt discount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentUnamortizedDiscount" xlink:to="us-gaap_DebtInstrumentUnamortizedDiscount_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NotesPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NotesPayable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_NotesPayable_lbl" xml:lang="en-US">Note payable originally due</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NotesPayable" xlink:to="us-gaap_NotesPayable_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_DebtInstrumentDueDate" xlink:href="onco-20231231.xsd#onco_DebtInstrumentDueDate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_DebtInstrumentDueDate_lbl" xml:lang="en-US">Note payable originally due</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DebtInstrumentDueDate" xlink:to="onco_DebtInstrumentDueDate_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_CashPaymentToTheSeller" xlink:href="onco-20231231.xsd#onco_CashPaymentToTheSeller"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_CashPaymentToTheSeller_lbl" xml:lang="en-US">Cash payment to the seller</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CashPaymentToTheSeller" xlink:to="onco_CashPaymentToTheSeller_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtConversionOriginalDebtAmount1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtConversionOriginalDebtAmount1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DebtConversionOriginalDebtAmount1_lbl" xml:lang="en-US">Conversion of debt</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtConversionOriginalDebtAmount1" xlink:to="us-gaap_DebtConversionOriginalDebtAmount1_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_DebtInstrumentDueTerm" xlink:href="onco-20231231.xsd#onco_DebtInstrumentDueTerm"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_DebtInstrumentDueTerm_lbl" xml:lang="en-US">Principal payments due</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DebtInstrumentDueTerm" xlink:to="onco_DebtInstrumentDueTerm_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AssetAcquisitionPriceOfAcquisitionExpected" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionPriceOfAcquisitionExpected"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AssetAcquisitionPriceOfAcquisitionExpected_lbl" xml:lang="en-US">Proteomedix acquisition (in Francs)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetAcquisitionPriceOfAcquisitionExpected" xlink:to="us-gaap_AssetAcquisitionPriceOfAcquisitionExpected_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_SaleOfUnits" xlink:href="onco-20231231.xsd#onco_SaleOfUnits"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SaleOfUnits_lbl" xml:lang="en-US">Sale of units</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SaleOfUnits" xlink:to="onco_SaleOfUnits_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesIssued"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SharesIssued_lbl" xml:lang="en-US">Share of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharesIssued" xlink:to="us-gaap_SharesIssued_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_SharesIssued_lbl0" xml:lang="en-US">Share issued of restricted common stock (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharesIssued" xlink:to="us-gaap_SharesIssued_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SaleOfStockPricePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SaleOfStockPricePerShare_lbl" xml:lang="en-US">Price per unit (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleOfStockPricePerShare" xlink:to="us-gaap_SaleOfStockPricePerShare_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ServicingLiabilityAtFairValueAdditions" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServicingLiabilityAtFairValueAdditions"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ServicingLiabilityAtFairValueAdditions_lbl" xml:lang="en-US">Fair value of Subscription agreement liability (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ServicingLiabilityAtFairValueAdditions" xlink:to="us-gaap_ServicingLiabilityAtFairValueAdditions_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ServicingLiabilityAtFairValueAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServicingLiabilityAtFairValueAmount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ServicingLiabilityAtFairValueAmount_lbl" xml:lang="en-US">Fair value of subscription agreement liability (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ServicingLiabilityAtFairValueAmount" xlink:to="us-gaap_ServicingLiabilityAtFairValueAmount_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProductLiabilityContingencyThirdPartyRecoveryPercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductLiabilityContingencyThirdPartyRecoveryPercentage"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ProductLiabilityContingencyThirdPartyRecoveryPercentage_lbl" xml:lang="en-US">Estimated probability percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProductLiabilityContingencyThirdPartyRecoveryPercentage" xlink:to="us-gaap_ProductLiabilityContingencyThirdPartyRecoveryPercentage_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherNotesPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNotesPayable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherNotesPayable_lbl" xml:lang="en-US">Notes payable due (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherNotesPayable" xlink:to="us-gaap_OtherNotesPayable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockLiquidationPreference" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockLiquidationPreference"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockLiquidationPreference_lbl" xml:lang="en-US">Liquidation per shares (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockLiquidationPreference" xlink:to="us-gaap_PreferredStockLiquidationPreference_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_SharesOfCommonStockRate" xlink:href="onco-20231231.xsd#onco_SharesOfCommonStockRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SharesOfCommonStockRate_lbl" xml:lang="en-US">Shares of common stock rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SharesOfCommonStockRate" xlink:to="onco_SharesOfCommonStockRate_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockConvertibleConversionPrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockConvertibleConversionPrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockConvertibleConversionPrice_lbl" xml:lang="en-US">Preferred investment option price per share (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockConvertibleConversionPrice" xlink:to="us-gaap_PreferredStockConvertibleConversionPrice_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockConvertibleSharesIssuable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockConvertibleSharesIssuable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockConvertibleSharesIssuable_lbl" xml:lang="en-US">Preferred stock designated</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockConvertibleSharesIssuable" xlink:to="us-gaap_PreferredStockConvertibleSharesIssuable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_lbl" xml:lang="en-US">Stock options vested</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:to="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PercentageOfIssuedOfCommonStock" xlink:href="onco-20231231.xsd#onco_PercentageOfIssuedOfCommonStock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PercentageOfIssuedOfCommonStock_lbl" xml:lang="en-US">Percentage of issued of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfIssuedOfCommonStock" xlink:to="onco_PercentageOfIssuedOfCommonStock_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PercentageOfOutstandingOfCommonStock" xlink:href="onco-20231231.xsd#onco_PercentageOfOutstandingOfCommonStock"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PercentageOfOutstandingOfCommonStock_lbl" xml:lang="en-US">Percentage of outstanding of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfOutstandingOfCommonStock" xlink:to="onco_PercentageOfOutstandingOfCommonStock_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PercentageOfCumulativeDividends" xlink:href="onco-20231231.xsd#onco_PercentageOfCumulativeDividends"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PercentageOfCumulativeDividends_lbl" xml:lang="en-US">Percentage of cumulative dividends</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfCumulativeDividends" xlink:to="onco_PercentageOfCumulativeDividends_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_NettingProceeds" xlink:href="onco-20231231.xsd#onco_NettingProceeds"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_NettingProceeds_lbl" xml:lang="en-US">Netting proceeds (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_NettingProceeds" xlink:to="onco_NettingProceeds_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PercentageOfOriginalIssuePrice" xlink:href="onco-20231231.xsd#onco_PercentageOfOriginalIssuePrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PercentageOfOriginalIssuePrice_lbl" xml:lang="en-US">Original issue price</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfOriginalIssuePrice" xlink:to="onco_PercentageOfOriginalIssuePrice_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CumulativeDividends" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CumulativeDividends"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CumulativeDividends_lbl" xml:lang="en-US">Cumulative dividends (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CumulativeDividends" xlink:to="us-gaap_CumulativeDividends_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DividendsPayableAmountPerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsPayableAmountPerShare"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DividendsPayableAmountPerShare_lbl" xml:lang="en-US">Dividends per share (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendsPayableAmountPerShare" xlink:to="us-gaap_DividendsPayableAmountPerShare_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssued1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssued1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssued1_lbl" xml:lang="en-US">Common stock issued (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssued1" xlink:to="us-gaap_StockIssued1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockOtherSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockOtherSharesOutstanding"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockOtherSharesOutstanding_lbl" xml:lang="en-US">Common stock outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockOtherSharesOutstanding" xlink:to="us-gaap_CommonStockOtherSharesOutstanding_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonUnitIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonUnitIssued"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonUnitIssued_lbl" xml:lang="en-US">Issued shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonUnitIssued" xlink:to="us-gaap_CommonUnitIssued_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharesIssuedPricePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesIssuedPricePerShare"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SharesIssuedPricePerShare_lbl" xml:lang="en-US">Common stock per share (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharesIssuedPricePerShare" xlink:to="us-gaap_SharesIssuedPricePerShare_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PercentageOfUnderwritingDiscount" xlink:href="onco-20231231.xsd#onco_PercentageOfUnderwritingDiscount"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PercentageOfUnderwritingDiscount_lbl" xml:lang="en-US">Percentage of underwriting discount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfUnderwritingDiscount" xlink:to="onco_PercentageOfUnderwritingDiscount_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherOwnershipInterestsOfferingCosts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherOwnershipInterestsOfferingCosts"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherOwnershipInterestsOfferingCosts_lbl" xml:lang="en-US">Offering costs (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherOwnershipInterestsOfferingCosts" xlink:to="us-gaap_OtherOwnershipInterestsOfferingCosts_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightUnissued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightUnissued"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ClassOfWarrantOrRightUnissued_lbl" xml:lang="en-US">Warrants to purchase</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightUnissued" xlink:to="us-gaap_ClassOfWarrantOrRightUnissued_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_lbl" xml:lang="en-US">Exercise price per share (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" xml:lang="en-US">Dividend yield</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_lbl" xml:lang="en-US">Shares remaining repurchased</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased" xlink:to="us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TreasuryStockAcquiredAverageCostPerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_TreasuryStockAcquiredAverageCostPerShare_lbl" xml:lang="en-US">Price per share (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TreasuryStockAcquiredAverageCostPerShare" xlink:to="us-gaap_TreasuryStockAcquiredAverageCostPerShare_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_lbl" xml:lang="en-US">Aggregate common stock value (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:to="us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_lbl" xml:lang="en-US">Warrants shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:to="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PlacementAgentFeeAndManagementFeePercentage" xlink:href="onco-20231231.xsd#onco_PlacementAgentFeeAndManagementFeePercentage"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PlacementAgentFeeAndManagementFeePercentage_lbl" xml:lang="en-US">Placement agent fee and management fee percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PlacementAgentFeeAndManagementFeePercentage" xlink:to="onco_PlacementAgentFeeAndManagementFeePercentage_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ConversionOfStockSharesConverted1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockSharesConverted1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ConversionOfStockSharesConverted1_lbl" xml:lang="en-US">Issued shares of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConversionOfStockSharesConverted1" xlink:to="us-gaap_ConversionOfStockSharesConverted1_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AggregateNumberOfSharesPercenatge" xlink:href="onco-20231231.xsd#onco_AggregateNumberOfSharesPercenatge"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AggregateNumberOfSharesPercenatge_lbl" xml:lang="en-US">Aggregate number of shares percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateNumberOfSharesPercenatge" xlink:to="onco_AggregateNumberOfSharesPercenatge_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ConversionOfStockSharesIssued1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConversionOfStockSharesIssued1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ConversionOfStockSharesIssued1_lbl" xml:lang="en-US">April Contingent Warrants issue</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConversionOfStockSharesIssued1" xlink:to="us-gaap_ConversionOfStockSharesIssued1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilities"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherLiabilities_lbl" xml:lang="en-US">Value of liability (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherLiabilities" xlink:to="us-gaap_OtherLiabilities_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_CancelledPreferredInvestmentOptionsShares" xlink:href="onco-20231231.xsd#onco_CancelledPreferredInvestmentOptionsShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_CancelledPreferredInvestmentOptionsShares_lbl" xml:lang="en-US">Cancelled preferred investment options</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CancelledPreferredInvestmentOptionsShares" xlink:to="onco_CancelledPreferredInvestmentOptionsShares_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PrefundedWarrantsExercised" xlink:href="onco-20231231.xsd#onco_PrefundedWarrantsExercised"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PrefundedWarrantsExercised_lbl" xml:lang="en-US">Pre-funded warrants exercised</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PrefundedWarrantsExercised" xlink:to="onco_PrefundedWarrantsExercised_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockDividendsShares" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendsShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockDividendsShares_lbl" xml:lang="en-US">Investment options</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockDividendsShares" xlink:to="us-gaap_PreferredStockDividendsShares_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockConvertibleConversionPriceDecrease" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockConvertibleConversionPriceDecrease"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PreferredStockConvertibleConversionPriceDecrease_lbl" xml:lang="en-US">Reduced exercise price (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockConvertibleConversionPriceDecrease" xlink:to="us-gaap_PreferredStockConvertibleConversionPriceDecrease_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherExpenses" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherExpenses"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherExpenses_lbl" xml:lang="en-US">(in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherExpenses" xlink:to="us-gaap_OtherExpenses_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OtherExpenses_lbl0" xml:lang="en-US">Accrued expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherExpenses" xlink:to="us-gaap_OtherExpenses_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_WarrantsIssuableUnderProvisionShares" xlink:href="onco-20231231.xsd#onco_WarrantsIssuableUnderProvisionShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_WarrantsIssuableUnderProvisionShares_lbl" xml:lang="en-US">Warrants issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WarrantsIssuableUnderProvisionShares" xlink:to="onco_WarrantsIssuableUnderProvisionShares_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_IncreaseInTheFairValueOfThePreferredInvestmentOptions" xlink:href="onco-20231231.xsd#onco_IncreaseInTheFairValueOfThePreferredInvestmentOptions"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_IncreaseInTheFairValueOfThePreferredInvestmentOptions_lbl" xml:lang="en-US">Increase in fair value of the preferred investment options (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IncreaseInTheFairValueOfThePreferredInvestmentOptions" xlink:to="onco_IncreaseInTheFairValueOfThePreferredInvestmentOptions_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalOther"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalOther_lbl" xml:lang="en-US">Reduction of additional paid in capital (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdjustmentsToAdditionalPaidInCapitalOther" xlink:to="us-gaap_AdjustmentsToAdditionalPaidInCapitalOther_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ContingentWarrantLiabilityShares" xlink:href="onco-20231231.xsd#onco_ContingentWarrantLiabilityShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ContingentWarrantLiabilityShares_lbl" xml:lang="en-US">Contingent warrant liability shares (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ContingentWarrantLiabilityShares" xlink:to="onco_ContingentWarrantLiabilityShares_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_SharesOfCommonStockIssued" xlink:href="onco-20231231.xsd#onco_SharesOfCommonStockIssued"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SharesOfCommonStockIssued_lbl" xml:lang="en-US">Shares of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SharesOfCommonStockIssued" xlink:to="onco_SharesOfCommonStockIssued_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_FixedCommissionRate" xlink:href="onco-20231231.xsd#onco_FixedCommissionRate"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_FixedCommissionRate_lbl" xml:lang="en-US">Fixed commission rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_FixedCommissionRate" xlink:to="onco_FixedCommissionRate_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockOptionExercisePriceIncrease" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockOptionExercisePriceIncrease"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockOptionExercisePriceIncrease_lbl" xml:lang="en-US">(in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockOptionExercisePriceIncrease" xlink:to="us-gaap_StockOptionExercisePriceIncrease_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockOptionExercisePriceDecrease" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockOptionExercisePriceDecrease"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockOptionExercisePriceDecrease_lbl" xml:lang="en-US">Reduced exercised price (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockOptionExercisePriceDecrease" xlink:to="us-gaap_StockOptionExercisePriceDecrease_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AggregateNetProceeds" xlink:href="onco-20231231.xsd#onco_AggregateNetProceeds"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AggregateNetProceeds_lbl" xml:lang="en-US">Aggregate net proceeds (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateNetProceeds" xlink:to="onco_AggregateNetProceeds_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_lbl" xml:lang="en-US">Issued shares of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction" xlink:to="us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesSubscribedButUnissued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesSubscribedButUnissued"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockSharesSubscribedButUnissued_lbl" xml:lang="en-US">Shares unissued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesSubscribedButUnissued" xlink:to="us-gaap_CommonStockSharesSubscribedButUnissued_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PercentageOfGrossProceeds" xlink:href="onco-20231231.xsd#onco_PercentageOfGrossProceeds"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PercentageOfGrossProceeds_lbl" xml:lang="en-US">Percentage of gross proceeds</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfGrossProceeds" xlink:to="onco_PercentageOfGrossProceeds_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LegalFees" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LegalFees"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LegalFees_lbl" xml:lang="en-US">Fees and expenses of legal (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LegalFees" xlink:to="us-gaap_LegalFees_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_LegalFees_lbl0" xml:lang="en-US">Legal expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LegalFees" xlink:to="us-gaap_LegalFees_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherGeneralExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherGeneralExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherGeneralExpense_lbl" xml:lang="en-US">Non-accountable expenses (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherGeneralExpense" xlink:to="us-gaap_OtherGeneralExpense_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PercentageOfCommonStockShares" xlink:href="onco-20231231.xsd#onco_PercentageOfCommonStockShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PercentageOfCommonStockShares_lbl" xml:lang="en-US">Percentage of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfCommonStockShares" xlink:to="onco_PercentageOfCommonStockShares_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_lbl" xml:lang="en-US">Warrants issuable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight" xlink:to="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding_lbl" xml:lang="en-US">Outstanding warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightOutstanding" xlink:to="us-gaap_ClassOfWarrantOrRightOutstanding_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding_lbl0" xml:lang="en-US">Cancellation of warrants issued (in Shares)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightOutstanding" xlink:to="us-gaap_ClassOfWarrantOrRightOutstanding_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharePrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SharePrice_lbl" xml:lang="en-US">Fair value per share (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharePrice" xlink:to="us-gaap_SharePrice_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_BusinessCombinationContingentConsiderationLiability_lbl" xml:lang="en-US">Fair value of the contingent warrant liability (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:to="us-gaap_BusinessCombinationContingentConsiderationLiability_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_lbl" xml:lang="en-US">Common stock reserved for issuance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:to="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" xml:lang="en-US">Available shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl" xml:lang="en-US">Weighted average grant date fair value (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_lbl" xml:lang="en-US">Aggregate fair value of stock options (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ExercisePrice" xlink:href="onco-20231231.xsd#onco_ExercisePrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ExercisePrice_lbl" xml:lang="en-US">options granted exercise price (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ExercisePrice" xlink:to="onco_ExercisePrice_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_GrantDateFairValueOfStockOption" xlink:href="onco-20231231.xsd#onco_GrantDateFairValueOfStockOption"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_GrantDateFairValueOfStockOption_lbl" xml:lang="en-US">Grant date fair value of stock option (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_GrantDateFairValueOfStockOption" xlink:to="onco_GrantDateFairValueOfStockOption_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense_lbl" xml:lang="en-US">Recognized stock based compensation expense (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense" xlink:to="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings_lbl" xml:lang="en-US">Restricted shares granted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings" xlink:to="us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_RestrictedSharesGrantedVestPercentage" xlink:href="onco-20231231.xsd#onco_RestrictedSharesGrantedVestPercentage"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_RestrictedSharesGrantedVestPercentage_lbl" xml:lang="en-US">Restricted shares granted vest</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RestrictedSharesGrantedVestPercentage" xlink:to="onco_RestrictedSharesGrantedVestPercentage_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited_lbl" xml:lang="en-US">Forfeited shares of restricted stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited" xlink:to="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" xml:lang="en-US">Vesting period</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_lbl" xml:lang="en-US">Stock options outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_lbl" xml:lang="en-US">Vested weighted average exercise price (in Dollars per share)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_lbl" xml:lang="en-US">Vested weighted average term</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_lbl" xml:lang="en-US">Vested intrinsic value (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharesHeldInEmployeeStockOptionPlanAllocated" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesHeldInEmployeeStockOptionPlanAllocated"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SharesHeldInEmployeeStockOptionPlanAllocated_lbl" xml:lang="en-US">Stock option</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharesHeldInEmployeeStockOptionPlanAllocated" xlink:to="us-gaap_SharesHeldInEmployeeStockOptionPlanAllocated_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" xml:lang="en-US">Unrecognized stock based compensation (in Dollars)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xml:lang="en-US">Weighted average period</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForServices"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices_lbl" xml:lang="en-US">Aggregate of stock options</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:to="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LeaseCost" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseCost"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LeaseCost_lbl" xml:lang="en-US">Leases office rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseCost" xlink:to="us-gaap_LeaseCost_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShortTermLeasePayments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermLeasePayments"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ShortTermLeasePayments_lbl" xml:lang="en-US">Short-term lease</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermLeasePayments" xlink:to="us-gaap_ShortTermLeasePayments_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsForRent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForRent"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PaymentsForRent_lbl" xml:lang="en-US">Rent expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsForRent" xlink:to="us-gaap_PaymentsForRent_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLeaseIncomeLeasePayments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLeaseIncomeLeasePayments"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OperatingLeaseLeaseIncomeLeasePayments_lbl" xml:lang="en-US">Variable lease expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLeaseIncomeLeasePayments" xlink:to="us-gaap_OperatingLeaseLeaseIncomeLeasePayments_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PercentageOfSubscription" xlink:href="onco-20231231.xsd#onco_PercentageOfSubscription"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PercentageOfSubscription_lbl" xml:lang="en-US">Percentage of subscription</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfSubscription" xlink:to="onco_PercentageOfSubscription_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AggregatePayments" xlink:href="onco-20231231.xsd#onco_AggregatePayments"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AggregatePayments_lbl" xml:lang="en-US">Aggregate payments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregatePayments" xlink:to="onco_AggregatePayments_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesSubjectToCompromiseEarlyContractTerminationFees" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesSubjectToCompromiseEarlyContractTerminationFees"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LiabilitiesSubjectToCompromiseEarlyContractTerminationFees_lbl" xml:lang="en-US">Termination fee</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesSubjectToCompromiseEarlyContractTerminationFees" xlink:to="us-gaap_LiabilitiesSubjectToCompromiseEarlyContractTerminationFees_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LaborAndRelatedExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LaborAndRelatedExpense"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_LaborAndRelatedExpense_lbl" xml:lang="en-US">Related expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LaborAndRelatedExpense" xlink:to="us-gaap_LaborAndRelatedExpense_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DividendsPaidinkind" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsPaidinkind"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_DividendsPaidinkind_lbl" xml:lang="en-US">Approximately amount paid</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendsPaidinkind" xlink:to="us-gaap_DividendsPaidinkind_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionAmountsOfTransaction" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RelatedPartyTransactionAmountsOfTransaction_lbl" xml:lang="en-US">Related party transactions amounts</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionAmountsOfTransaction" xlink:to="us-gaap_RelatedPartyTransactionAmountsOfTransaction_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherReceivables" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherReceivables"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OtherReceivables_lbl" xml:lang="en-US">Related party receivable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherReceivables" xlink:to="us-gaap_OtherReceivables_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RepaymentsOfRelatedPartyDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfRelatedPartyDebt"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_RepaymentsOfRelatedPartyDebt_lbl" xml:lang="en-US">Repayment of related party</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RepaymentsOfRelatedPartyDebt" xlink:to="us-gaap_RepaymentsOfRelatedPartyDebt_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_MiscellaneousExpenses" xlink:href="onco-20231231.xsd#onco_MiscellaneousExpenses"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CollaborativeArrangementAccountingPolicy_lbl" xml:lang="en-US">Collaborative Agreements</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CollaborativeArrangementAccountingPolicy" xlink:to="us-gaap_CollaborativeArrangementAccountingPolicy_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueRecognitionPolicyTextBlock" xlink:to="us-gaap_RevenueRecognitionPolicyTextBlock_lbl"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_ResearchAndDevelopmentExpensePolicy_lbl" xml:lang="en-US">Research and Development</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxPolicyTextBlock" xlink:to="us-gaap_IncomeTaxPolicyTextBlock_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ComprehensiveIncomePolicyPolicyTextBlock" xlink:to="us-gaap_ComprehensiveIncomePolicyPolicyTextBlock_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:to="us-gaap_FairValueOfFinancialInstrumentsPolicy_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_TreasuryStockPolicyPolicyTextBlock" xlink:to="onco_TreasuryStockPolicyPolicyTextBlock_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EarningsPerSharePolicyTextBlock" xlink:to="us-gaap_EarningsPerSharePolicyTextBlock_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:to="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_OnconetixMember" xlink:to="onco_OnconetixMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IPOMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IPOMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_IPOMember_lbl" xml:lang="en-US">IPO [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IPOMember" xlink:to="us-gaap_IPOMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SubsequentEventMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_SubsequentEventMember_lbl" xml:lang="en-US">Subsequent Event [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventMember" xlink:to="us-gaap_SubsequentEventMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ENTADFIMember" xlink:href="onco-20231231.xsd#onco_ENTADFIMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ENTADFIMember_lbl" xml:lang="en-US">ENTADFI [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ENTADFIMember" xlink:to="onco_ENTADFIMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_PropertyPlantAndEquipmentMember_lbl" xml:lang="en-US">Fixed Assets [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentMember" xlink:to="us-gaap_PropertyPlantAndEquipmentMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AssetPurchaseAgreementMember" xlink:href="onco-20231231.xsd#onco_AssetPurchaseAgreementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AssetPurchaseAgreementMember_lbl" xml:lang="en-US">Asset Purchase Agreement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AssetPurchaseAgreementMember" xlink:to="onco_AssetPurchaseAgreementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_MilestonePaymentsMember" xlink:href="onco-20231231.xsd#onco_MilestonePaymentsMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_MilestonePaymentsMember_lbl" xml:lang="en-US">Milestone Payments [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_MilestonePaymentsMember" xlink:to="onco_MilestonePaymentsMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PharmaceuticalServicesLLCMember" xlink:href="onco-20231231.xsd#onco_PharmaceuticalServicesLLCMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PharmaceuticalServicesLLCMember_lbl" xml:lang="en-US">Pharmaceutical Services, LLC [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PharmaceuticalServicesLLCMember" xlink:to="onco_PharmaceuticalServicesLLCMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ManagementServicesAgreementMember" xlink:href="onco-20231231.xsd#onco_ManagementServicesAgreementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ManagementServicesAgreementMember_lbl" xml:lang="en-US">Management Services Agreement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ManagementServicesAgreementMember" xlink:to="onco_ManagementServicesAgreementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_WraSerAPAMember" xlink:href="onco-20231231.xsd#onco_WraSerAPAMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_WraSerAPAMember_lbl" xml:lang="en-US">WraSer APA [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WraSerAPAMember" xlink:to="onco_WraSerAPAMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_BankruptcyCourtMember" xlink:href="onco-20231231.xsd#onco_BankruptcyCourtMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_BankruptcyCourtMember_lbl" xml:lang="en-US">Bankruptcy Court [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BankruptcyCourtMember" xlink:to="onco_BankruptcyCourtMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_WraSerMSAMember" xlink:href="onco-20231231.xsd#onco_WraSerMSAMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_WraSerMSAMember_lbl" xml:lang="en-US">WraSer MSA [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WraSerMSAMember" xlink:to="onco_WraSerMSAMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_SeriesBConvertiblePreferredStockMember" xlink:href="onco-20231231.xsd#onco_SeriesBConvertiblePreferredStockMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SeriesBConvertiblePreferredStockMember_lbl" xml:lang="en-US">Series B Convertible Preferred Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SeriesBConvertiblePreferredStockMember" xlink:to="onco_SeriesBConvertiblePreferredStockMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_OlogyBioservicesIncMember" xlink:href="onco-20231231.xsd#onco_OlogyBioservicesIncMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_OlogyBioservicesIncMember_lbl" xml:lang="en-US">Ology MSA. [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_OlogyBioservicesIncMember" xlink:to="onco_OlogyBioservicesIncMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="onco_OlogyBioservicesIncMember_lbl0" xml:lang="en-US">Ology Bioservices, Inc [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_OlogyBioservicesIncMember" xlink:to="onco_OlogyBioservicesIncMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_CincinnatiChildrensHospitalMedicalCenterMember" xlink:href="onco-20231231.xsd#onco_CincinnatiChildrensHospitalMedicalCenterMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_CincinnatiChildrensHospitalMedicalCenterMember_lbl" xml:lang="en-US">CHMC Agreement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CincinnatiChildrensHospitalMedicalCenterMember" xlink:to="onco_CincinnatiChildrensHospitalMedicalCenterMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_RegulatoryMilestonesMember" xlink:href="onco-20231231.xsd#onco_RegulatoryMilestonesMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_RegulatoryMilestonesMember_lbl" xml:lang="en-US">Regulatory milestones [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RegulatoryMilestonesMember" xlink:to="onco_RegulatoryMilestonesMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommercialAndIndustrialSectorMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialAndIndustrialSectorMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_CommercialAndIndustrialSectorMember_lbl" xml:lang="en-US">Commercial milestones [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommercialAndIndustrialSectorMember" xlink:to="us-gaap_CommercialAndIndustrialSectorMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_OxfordUniversityInnovationLimitedMember" xlink:href="onco-20231231.xsd#onco_OxfordUniversityInnovationLimitedMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_OxfordUniversityInnovationLimitedMember_lbl" xml:lang="en-US">Oxford University Innovation Limited [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_OxfordUniversityInnovationLimitedMember" xlink:to="onco_OxfordUniversityInnovationLimitedMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_OUIAgreementMember" xlink:href="onco-20231231.xsd#onco_OUIAgreementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_OUIAgreementMember_lbl" xml:lang="en-US">OUI Agreement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_OUIAgreementMember" xlink:to="onco_OUIAgreementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_DevelopmentMilestonesMember" xlink:href="onco-20231231.xsd#onco_DevelopmentMilestonesMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_DevelopmentMilestonesMember_lbl" xml:lang="en-US">Development milestone [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DevelopmentMilestonesMember" xlink:to="onco_DevelopmentMilestonesMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_StJudeChildrensHospitalMember" xlink:href="onco-20231231.xsd#onco_StJudeChildrensHospitalMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_StJudeChildrensHospitalMember_lbl" xml:lang="en-US">St. Jude Children&#8217;s Hospital [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StJudeChildrensHospitalMember" xlink:to="onco_StJudeChildrensHospitalMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UTHealthAgreementMember" xlink:href="onco-20231231.xsd#onco_UTHealthAgreementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UTHealthAgreementMember_lbl" xml:lang="en-US">UT Health Agreement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UTHealthAgreementMember" xlink:to="onco_UTHealthAgreementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UniversityOfTexasHealthScienceCenterAtSanAntonioMember" xlink:href="onco-20231231.xsd#onco_UniversityOfTexasHealthScienceCenterAtSanAntonioMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UniversityOfTexasHealthScienceCenterAtSanAntonioMember_lbl" xml:lang="en-US">University of Texas Health Science Center at San Antonio [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UniversityOfTexasHealthScienceCenterAtSanAntonioMember" xlink:to="onco_UniversityOfTexasHealthScienceCenterAtSanAntonioMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_CoDevelopmentAgreementMember" xlink:href="onco-20231231.xsd#onco_CoDevelopmentAgreementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_CoDevelopmentAgreementMember_lbl" xml:lang="en-US">Co Development Agreement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CoDevelopmentAgreementMember" xlink:to="onco_CoDevelopmentAgreementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_VendorAgreementMember" xlink:href="onco-20231231.xsd#onco_VendorAgreementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_VendorAgreementMember_lbl" xml:lang="en-US">Vendor Agreement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_VendorAgreementMember" xlink:to="onco_VendorAgreementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_LaboratorCorporationOfAmericaMember" xlink:href="onco-20231231.xsd#onco_LaboratorCorporationOfAmericaMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_LaboratorCorporationOfAmericaMember_lbl" xml:lang="en-US">Laborator Corporation of America [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_LaboratorCorporationOfAmericaMember" xlink:to="onco_LaboratorCorporationOfAmericaMember_lbl"/>
    <loc xlink:type="locator" xlink:label="srt_ScenarioForecastMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioForecastMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_ScenarioForecastMember_lbl" xml:lang="en-US">Forecast [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ScenarioForecastMember" xlink:to="srt_ScenarioForecastMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_NotePayableMember" xlink:href="onco-20231231.xsd#onco_NotePayableMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_NotePayableMember_lbl" xml:lang="en-US">Note Payable [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_NotePayableMember" xlink:to="onco_NotePayableMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ProteomedixAcquisitionMember" xlink:href="onco-20231231.xsd#onco_ProteomedixAcquisitionMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ProteomedixAcquisitionMember_lbl" xml:lang="en-US">Proteomedix Acquisition [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ProteomedixAcquisitionMember" xlink:to="onco_ProteomedixAcquisitionMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_SeriesSeedPreferredStockMember" xlink:href="onco-20231231.xsd#onco_SeriesSeedPreferredStockMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SeriesSeedPreferredStockMember_lbl" xml:lang="en-US">Series Seed Convertible Preferred Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SeriesSeedPreferredStockMember" xlink:to="onco_SeriesSeedPreferredStockMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="onco_SeriesSeedPreferredStockMember_lbl0" xml:lang="en-US">Series Seed Preferred Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SeriesSeedPreferredStockMember" xlink:to="onco_SeriesSeedPreferredStockMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_TreasuryStocksMember" xlink:href="onco-20231231.xsd#onco_TreasuryStocksMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_TreasuryStocksMember_lbl" xml:lang="en-US">Treasury Stocks [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_TreasuryStocksMember" xlink:to="onco_TreasuryStocksMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_April2022PrivatePlacementMember" xlink:href="onco-20231231.xsd#onco_April2022PrivatePlacementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_April2022PrivatePlacementMember_lbl" xml:lang="en-US">April 2022 Private Placement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_April2022PrivatePlacementMember" xlink:to="onco_April2022PrivatePlacementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_HCWainwrightCoLLCMember" xlink:href="onco-20231231.xsd#onco_HCWainwrightCoLLCMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_HCWainwrightCoLLCMember_lbl" xml:lang="en-US">H.C. Wainwright &amp; Co., LLC [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_HCWainwrightCoLLCMember" xlink:to="onco_HCWainwrightCoLLCMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AprilContingentWarrantsMember" xlink:href="onco-20231231.xsd#onco_AprilContingentWarrantsMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AprilContingentWarrantsMember_lbl" xml:lang="en-US">April Contingent Warrants [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AprilContingentWarrantsMember" xlink:to="onco_AprilContingentWarrantsMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_August2022PrivatePlacementMember" xlink:href="onco-20231231.xsd#onco_August2022PrivatePlacementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_August2022PrivatePlacementMember_lbl" xml:lang="en-US">August 2022 Private Placement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_August2022PrivatePlacementMember" xlink:to="onco_August2022PrivatePlacementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AugustWainwrightWarrantsMember" xlink:href="onco-20231231.xsd#onco_AugustWainwrightWarrantsMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AugustWainwrightWarrantsMember_lbl" xml:lang="en-US">August Wainwright Warrants [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AugustWainwrightWarrantsMember" xlink:to="onco_AugustWainwrightWarrantsMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_AugustContingentWarrantsMember" xlink:href="onco-20231231.xsd#onco_AugustContingentWarrantsMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_AugustContingentWarrantsMember_lbl" xml:lang="en-US">August Contingent Warrants [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AugustContingentWarrantsMember" xlink:to="onco_AugustContingentWarrantsMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_MarketOfferingAgreementMember" xlink:href="onco-20231231.xsd#onco_MarketOfferingAgreementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_MarketOfferingAgreementMember_lbl" xml:lang="en-US">Market Offering Agreement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_MarketOfferingAgreementMember" xlink:to="onco_MarketOfferingAgreementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_WarrantInducementMember" xlink:href="onco-20231231.xsd#onco_WarrantInducementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_WarrantInducementMember_lbl" xml:lang="en-US">Warrant Inducement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WarrantInducementMember" xlink:to="onco_WarrantInducementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_InducementPIOSharesMember" xlink:href="onco-20231231.xsd#onco_InducementPIOSharesMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_InducementPIOSharesMember_lbl" xml:lang="en-US">Inducement PIO Shares [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_InducementPIOSharesMember" xlink:to="onco_InducementPIOSharesMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_TwoThousandNinteenEquityIncentivePlanMember" xlink:href="onco-20231231.xsd#onco_TwoThousandNinteenEquityIncentivePlanMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_TwoThousandNinteenEquityIncentivePlanMember_lbl" xml:lang="en-US">2019 Equity Incentive Plan [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_TwoThousandNinteenEquityIncentivePlanMember" xlink:to="onco_TwoThousandNinteenEquityIncentivePlanMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_TwoThousandTwentyTwoEquityIncentivePlanMember" xlink:href="onco-20231231.xsd#onco_TwoThousandTwentyTwoEquityIncentivePlanMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_TwoThousandTwentyTwoEquityIncentivePlanMember_lbl" xml:lang="en-US">2022 Equity Incentive Plan [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_TwoThousandTwentyTwoEquityIncentivePlanMember" xlink:to="onco_TwoThousandTwentyTwoEquityIncentivePlanMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_TwoThousandTwentyTwoPlanMember" xlink:href="onco-20231231.xsd#onco_TwoThousandTwentyTwoPlanMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_TwoThousandTwentyTwoPlanMember_lbl" xml:lang="en-US">2022 Plan [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_TwoThousandTwentyTwoPlanMember" xlink:to="onco_TwoThousandTwentyTwoPlanMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="onco_TwoThousandTwentyTwoPlanMember_lbl0" xml:lang="en-US">Two Thousand Twenty Two Plan [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_TwoThousandTwentyTwoPlanMember" xlink:to="onco_TwoThousandTwentyTwoPlanMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="srt_ChiefExecutiveOfficerMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ChiefExecutiveOfficerMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_ChiefExecutiveOfficerMember_lbl" xml:lang="en-US">Chief Executive Officer [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ChiefExecutiveOfficerMember" xlink:to="srt_ChiefExecutiveOfficerMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ChiefBusinessOfficerMember" xlink:href="onco-20231231.xsd#onco_ChiefBusinessOfficerMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_ChiefBusinessOfficerMember_lbl" xml:lang="en-US">CBO&#8217;s [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ChiefBusinessOfficerMember" xlink:to="onco_ChiefBusinessOfficerMember_lbl"/>
    <loc xlink:type="locator" xlink:label="srt_ChiefFinancialOfficerMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ChiefFinancialOfficerMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_ChiefFinancialOfficerMember_lbl" xml:lang="en-US">Chief Financial Officer [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ChiefFinancialOfficerMember" xlink:to="srt_ChiefFinancialOfficerMember_lbl"/>
    <loc xlink:type="locator" xlink:label="srt_DirectorMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_DirectorMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="srt_DirectorMember_lbl" xml:lang="en-US">Board of Directors [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_DirectorMember" xlink:to="srt_DirectorMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="srt_DirectorMember_lbl0" xml:lang="en-US">Director [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_DirectorMember" xlink:to="srt_DirectorMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_January2024Member" xlink:href="onco-20231231.xsd#onco_January2024Member"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_January2024Member_lbl" xml:lang="en-US">January 2024 [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_January2024Member" xlink:to="onco_January2024Member_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_August2024Member" xlink:href="onco-20231231.xsd#onco_August2024Member"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_August2024Member_lbl" xml:lang="en-US">August 2024 [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_August2024Member" xlink:to="onco_August2024Member_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_August2025Member" xlink:href="onco-20231231.xsd#onco_August2025Member"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_August2025Member_lbl" xml:lang="en-US">August 2025 [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_August2025Member" xlink:to="onco_August2025Member_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_PMXOptionPlanMember" xlink:href="onco-20231231.xsd#onco_PMXOptionPlanMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_PMXOptionPlanMember_lbl" xml:lang="en-US">PMX Option Plan [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PMXOptionPlanMember" xlink:to="onco_PMXOptionPlanMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_UnvestedRestrictedStockMember" xlink:href="onco-20231231.xsd#onco_UnvestedRestrictedStockMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_UnvestedRestrictedStockMember_lbl" xml:lang="en-US">Unvested Restricted Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnvestedRestrictedStockMember" xlink:to="onco_UnvestedRestrictedStockMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_SettlementAgreementMember" xlink:href="onco-20231231.xsd#onco_SettlementAgreementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SettlementAgreementMember_lbl" xml:lang="en-US">Settlement Agreement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SettlementAgreementMember" xlink:to="onco_SettlementAgreementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_CEOMember" xlink:href="onco-20231231.xsd#onco_CEOMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_CEOMember_lbl" xml:lang="en-US">CEO [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CEOMember" xlink:to="onco_CEOMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_CBOMember" xlink:href="onco-20231231.xsd#onco_CBOMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_CBOMember_lbl" xml:lang="en-US">CBO [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CBOMember" xlink:to="onco_CBOMember_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_NonConvertibleDebentureMember" xlink:href="onco-20231231.xsd#onco_NonConvertibleDebentureMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_NonConvertibleDebentureMember_lbl" xml:lang="en-US">Non convertible debenture [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_NonConvertibleDebentureMember" xlink:to="onco_NonConvertibleDebentureMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OperatingIncomeLossMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLossMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="us-gaap_OperatingIncomeLossMember_lbl" xml:lang="en-US">Net Operating Loss [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingIncomeLossMember" xlink:to="us-gaap_OperatingIncomeLossMember_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:label="us-gaap_OperatingIncomeLossMember_lbl0" xml:lang="en-US">Operating Income (Loss) [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingIncomeLossMember" xlink:to="us-gaap_OperatingIncomeLossMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_SubscriptionAgreementMember" xlink:href="onco-20231231.xsd#onco_SubscriptionAgreementMember"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:label="onco_SubscriptionAgreementMember_lbl" xml:lang="en-US">Subscription Agreement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SubscriptionAgreementMember" xlink:to="onco_SubscriptionAgreementMember_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RelatedPartyDomain_lbl" xml:lang="en-US">Related Party, Type [Domain]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyDomain" xlink:to="us-gaap_RelatedPartyDomain_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StatementTable_lbl" xml:lang="en-US">Statement [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementTable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StatementLineItems_lbl" xml:lang="en-US">Statement [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementLineItems_lbl"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessAcquisitionLineItems_lbl" xml:lang="en-US">Acquisitions [Line Items]</label>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_NotesPayableDetailsTable" xlink:to="onco_NotesPayableDetailsTable_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentLineItems_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart3LineItems" xlink:to="onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart3LineItems_lbl"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PlanNameDomain_lbl" xml:lang="en-US">Plan Name [Domain]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PlanNameDomain" xlink:to="us-gaap_PlanNameDomain_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart4Table" xlink:href="onco-20231231.xsd#onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart4Table"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart4Table_lbl" xml:lang="en-US">Convertible Redeemable Preferred Stock and Stockholders&apos; Equity (Details) - Part 4 [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart4Table" xlink:to="onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart4Table_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart4LineItems" xlink:href="onco-20231231.xsd#onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart4LineItems"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart4LineItems_lbl" xml:lang="en-US">Convertible Redeemable Preferred Stock and Stockholders&apos; Equity (Details) - Part 4 [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart4LineItems" xlink:to="onco_ConvertibleRedeemablePreferredStockandStockholdersEquityDetailsPart4LineItems_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_lbl" xml:lang="en-US">Research and Development Arrangement, Contract to Perform for Others, Type [Domain]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:to="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_CommitmentsandContingenciesDetailsTable" xlink:href="onco-20231231.xsd#onco_CommitmentsandContingenciesDetailsTable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_CommitmentsandContingenciesDetailsTable_lbl" xml:lang="en-US">Commitments and Contingencies (Details) [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CommitmentsandContingenciesDetailsTable" xlink:to="onco_CommitmentsandContingenciesDetailsTable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherCommitmentsLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherCommitmentsLineItems_lbl" xml:lang="en-US">Commitments and Contingencies [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherCommitmentsLineItems" xlink:to="us-gaap_OtherCommitmentsLineItems_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_RelatedPartyTransactionsDetailsTable" xlink:href="onco-20231231.xsd#onco_RelatedPartyTransactionsDetailsTable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_RelatedPartyTransactionsDetailsTable_lbl" xml:lang="en-US">Related Party Transactions (Details) [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RelatedPartyTransactionsDetailsTable" xlink:to="onco_RelatedPartyTransactionsDetailsTable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RelatedPartyTransactionLineItems_lbl" xml:lang="en-US">Related Party Transactions [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_RelatedPartyTransactionLineItems_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_IncomeTaxesDetailsTable" xlink:href="onco-20231231.xsd#onco_IncomeTaxesDetailsTable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_IncomeTaxesDetailsTable_lbl" xml:lang="en-US">Income Taxes (Details) [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IncomeTaxesDetailsTable" xlink:to="onco_IncomeTaxesDetailsTable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncomeTaxContingencyLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxContingencyLineItems"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxContingencyLineItems_lbl" xml:lang="en-US">Income Taxes [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxContingencyLineItems" xlink:to="us-gaap_IncomeTaxContingencyLineItems_lbl"/>
    <loc xlink:type="locator" xlink:label="onco_SubsequentEventsDetailsTable" xlink:href="onco-20231231.xsd#onco_SubsequentEventsDetailsTable"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_SubsequentEventsDetailsTable_lbl" xml:lang="en-US">Subsequent Events (Details) [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SubsequentEventsDetailsTable" xlink:to="onco_SubsequentEventsDetailsTable_lbl"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SubsequentEventLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventLineItems"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SubsequentEventLineItems_lbl" xml:lang="en-US">Subsequent Events [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventLineItems" xlink:to="us-gaap_SubsequentEventLineItems_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AccruedDeferredOfferingCosts_lbl0" xml:lang="en-US">Accrued deferred offering costs.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AccruedDeferredOfferingCosts" xlink:to="onco_AccruedDeferredOfferingCosts_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AccruedResearchAndDevelopmentCurrent_lbl0" xml:lang="en-US">Accrued research and development</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AccruedResearchAndDevelopmentCurrent" xlink:to="onco_AccruedResearchAndDevelopmentCurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AcquisitionsPolicyTextBlock_lbl0" xml:lang="en-US">Disclosure of policy of acquisitions.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AcquisitionsPolicyTextBlock" xlink:to="onco_AcquisitionsPolicyTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AggregateAgreementAmountInitialAgreement_lbl0" xml:lang="en-US">Amount of aggregate Agreement amount initial agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateAgreementAmountInitialAgreement" xlink:to="onco_AggregateAgreementAmountInitialAgreement_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AggregateNetProceeds_lbl0" xml:lang="en-US">Aggregate net proceeds.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateNetProceeds" xlink:to="onco_AggregateNetProceeds_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AggregateNumberOfSharesPercenatge_lbl0" xml:lang="en-US">Percenatge of aggregate number of shares.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateNumberOfSharesPercenatge" xlink:to="onco_AggregateNumberOfSharesPercenatge_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AggregatePayments_lbl0" xml:lang="en-US">Aggregate payments.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregatePayments" xlink:to="onco_AggregatePayments_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AggregatePurchaseShares_lbl1" xml:lang="en-US">Number of aggregate purchase shares.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregatePurchaseShares" xlink:to="onco_AggregatePurchaseShares_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AggregateRoyaltiesAmount_lbl0" xml:lang="en-US">Aggregate royalties amount.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateRoyaltiesAmount" xlink:to="onco_AggregateRoyaltiesAmount_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AggregateeAmount_lbl0" xml:lang="en-US">Aggregate amount.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateeAmount" xlink:to="onco_AggregateeAmount_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AlternativeInvestmentsRate_lbl0" xml:lang="en-US">Alternative investments rate.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AlternativeInvestmentsRate" xlink:to="onco_AlternativeInvestmentsRate_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AmortizationOfNetGain_lbl0" xml:lang="en-US">Amortization of net gain.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AmortizationOfNetGain" xlink:to="onco_AmortizationOfNetGain_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AmountOfOtherPartyPayments_lbl0" xml:lang="en-US">Amount of cash outflow to acquire investments classified as other.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AmountOfOtherPartyPayments" xlink:to="onco_AmountOfOtherPartyPayments_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AssetAcquisitionConsiderationTransferredENTADFIIntangible_lbl0" xml:lang="en-US">Amount of asset acquisition consideration transferred ENTADFI intangible.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AssetAcquisitionConsiderationTransferredENTADFIIntangible" xlink:to="onco_AssetAcquisitionConsiderationTransferredENTADFIIntangible_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_AssetAcquisitionConsiderationTransferredInventory_lbl0" xml:lang="en-US">Amount of asset acquisition, consideration transferred, inventory.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AssetAcquisitionConsiderationTransferredInventory" xlink:to="onco_AssetAcquisitionConsiderationTransferredInventory_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpenses_lbl0" xml:lang="en-US">Amount of liabilities accrued expenses.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpenses" xlink:to="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpenses_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNotePayable_lbl0" xml:lang="en-US">Amount of note payable.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNotePayable" xlink:to="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNotePayable_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPensionBenefitObligation_lbl0" xml:lang="en-US">Amount of pension benefit obligation.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPensionBenefitObligation" xlink:to="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPensionBenefitObligation_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedProductRightsForDevelopedTechnology_lbl0" xml:lang="en-US">Amount of product rights for developed technology.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedProductRightsForDevelopedTechnology" xlink:to="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedProductRightsForDevelopedTechnology_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRightofUseAsset_lbl0" xml:lang="en-US">Right of use asset.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRightofUseAsset" xlink:to="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRightofUseAsset_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesCustomerRelationships_lbl0" xml:lang="en-US">Amount of customer relationships.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesCustomerRelationships" xlink:to="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesCustomerRelationships_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_BusinessTransactionYeare_lbl0" xml:lang="en-US">Business transaction yeare.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessTransactionYeare" xlink:to="onco_BusinessTransactionYeare_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_CancelledPreferredInvestmentOptionsShares_lbl0" xml:lang="en-US">Number of shares (or other type of equity) cancelled during the period.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CancelledPreferredInvestmentOptionsShares" xlink:to="onco_CancelledPreferredInvestmentOptionsShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_CashPaymentToTheSeller_lbl0" xml:lang="en-US">The payment to the seller in the form of cash.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CashPaymentToTheSeller" xlink:to="onco_CashPaymentToTheSeller_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ChangeInFairValueOfSubscriptionAgreementLiability_lbl0" xml:lang="en-US">Change in fair value of subscription agreement liability.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ChangeInFairValueOfSubscriptionAgreementLiability" xlink:to="onco_ChangeInFairValueOfSubscriptionAgreementLiability_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ChangeInPensionBenefitObligation_lbl0" xml:lang="en-US">Change in pension benefit obligation,</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ChangeInPensionBenefitObligation" xlink:to="onco_ChangeInPensionBenefitObligation_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_CommercialSaleTerm_lbl0" xml:lang="en-US">Commercial sale term.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CommercialSaleTerm" xlink:to="onco_CommercialSaleTerm_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ContingentWarrantLiabilityShares_lbl0" xml:lang="en-US">Shares of contingent warrant liability.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ContingentWarrantLiabilityShares" xlink:to="onco_ContingentWarrantLiabilityShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_CostPlusPercentage_lbl0" xml:lang="en-US">Cost plus, percentage.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CostPlusPercentage" xlink:to="onco_CostPlusPercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_DebtInstrumentDueDate_lbl0" xml:lang="en-US">Debt Instrument due date.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DebtInstrumentDueDate" xlink:to="onco_DebtInstrumentDueDate_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_DebtInstrumentDueTerm_lbl0" xml:lang="en-US">Debt instrument due term.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DebtInstrumentDueTerm" xlink:to="onco_DebtInstrumentDueTerm_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_DebtSecuritiesAndCash_lbl0" xml:lang="en-US">Debt securities and cash.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DebtSecuritiesAndCash" xlink:to="onco_DebtSecuritiesAndCash_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_DeferredOfferingCostsPreviouslyPrepaid_lbl0" xml:lang="en-US">Amount of deferred offering costs previously prepaid.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DeferredOfferingCostsPreviouslyPrepaid" xlink:to="onco_DeferredOfferingCostsPreviouslyPrepaid_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_DefinedBenefitPlanBenefitObligationOrdinaryContributionsPaidByEmployees_lbl0" xml:lang="en-US">Ordinary contributions paid by employees.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DefinedBenefitPlanBenefitObligationOrdinaryContributionsPaidByEmployees" xlink:to="onco_DefinedBenefitPlanBenefitObligationOrdinaryContributionsPaidByEmployees_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_DefinedBenefitPlanPlanAssetsOrdinaryContributionsPaidByEmployees_lbl0" xml:lang="en-US">Ordinary contributions paid by employees.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DefinedBenefitPlanPlanAssetsOrdinaryContributionsPaidByEmployees" xlink:to="onco_DefinedBenefitPlanPlanAssetsOrdinaryContributionsPaidByEmployees_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_EffectOfBusinessCombination_lbl0" xml:lang="en-US">Effect of business combination.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_EffectOfBusinessCombination" xlink:to="onco_EffectOfBusinessCombination_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_EffectOfSettlement_lbl0" xml:lang="en-US">Effect of settlement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_EffectOfSettlement" xlink:to="onco_EffectOfSettlement_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseStateRateAdjustment_lbl0" xml:lang="en-US">Amount of state rate adjustment.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseStateRateAdjustment" xlink:to="onco_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseStateRateAdjustment_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_EquitySecuritiesRate_lbl0" xml:lang="en-US">Equity securities rate.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_EquitySecuritiesRate" xlink:to="onco_EquitySecuritiesRate_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ExerciseOfPrefundedWarrants_lbl0" xml:lang="en-US">Amount of exercise of pre-funded warrants.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ExerciseOfPrefundedWarrants" xlink:to="onco_ExerciseOfPrefundedWarrants_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ExerciseOfPrefundedWarrantsinShares_lbl0" xml:lang="en-US">Exercise of pre-funded warrants.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ExerciseOfPrefundedWarrantsinShares" xlink:to="onco_ExerciseOfPrefundedWarrantsinShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ExercisePrice_lbl0" xml:lang="en-US">Exercise price per share.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ExercisePrice" xlink:to="onco_ExercisePrice_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_Exerciseofprefundedwarrants_lbl0" xml:lang="en-US">Exercise of pre funded warrants.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_Exerciseofprefundedwarrants" xlink:to="onco_Exerciseofprefundedwarrants_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_FiniteLivedIntangibleAssetCost_lbl0" xml:lang="en-US">Represents the amount of finite lived intangible assets cost.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_FiniteLivedIntangibleAssetCost" xlink:to="onco_FiniteLivedIntangibleAssetCost_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_FiniteLivedIntangibleAssetsAccumulatedAmortizationEffectOfCurrencyTranslation_lbl0" xml:lang="en-US">Represents the amount of effect of currency translation.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_FiniteLivedIntangibleAssetsAccumulatedAmortizationEffectOfCurrencyTranslation" xlink:to="onco_FiniteLivedIntangibleAssetsAccumulatedAmortizationEffectOfCurrencyTranslation_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_FixedCommissionRate_lbl0" xml:lang="en-US">Percentage of fixed commission.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_FixedCommissionRate" xlink:to="onco_FixedCommissionRate_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_GainLossOnRelatedPartyReceivable_lbl0" xml:lang="en-US">Amount of gain (loss) on related party receivable.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_GainLossOnRelatedPartyReceivable" xlink:to="onco_GainLossOnRelatedPartyReceivable_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_GrantDateFairValueOfStockOption_lbl0" xml:lang="en-US">Grant date fair value of stock option.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_GrantDateFairValueOfStockOption" xlink:to="onco_GrantDateFairValueOfStockOption_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_GrossPayPercentage_lbl0" xml:lang="en-US">The percentage of gross pay.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_GrossPayPercentage" xlink:to="onco_GrossPayPercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ImpairmentOfIntangibleAssetExcludingGoodwill_lbl0" xml:lang="en-US">The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of an intangible asset (excluding goodwill) to fair value.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ImpairmentOfIntangibleAssetExcludingGoodwill" xlink:to="onco_ImpairmentOfIntangibleAssetExcludingGoodwill_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ImpairmentRate_lbl0" xml:lang="en-US">Impairment rate.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ImpairmentRate" xlink:to="onco_ImpairmentRate_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_IncomeTaxReconciliationNondeductibleExpenseDerivativeLiability_lbl0" xml:lang="en-US">Amount of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to nondeductible expense for award under derivative liability.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IncomeTaxReconciliationNondeductibleExpenseDerivativeLiability" xlink:to="onco_IncomeTaxReconciliationNondeductibleExpenseDerivativeLiability_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_IncomeTaxReconciliationNondeductibleExpenseOfficersCompensation_lbl0" xml:lang="en-US">Officer&#8217;s compensation.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IncomeTaxReconciliationNondeductibleExpenseOfficersCompensation" xlink:to="onco_IncomeTaxReconciliationNondeductibleExpenseOfficersCompensation_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_IncreaseInTheFairValueOfThePreferredInvestmentOptions_lbl0" xml:lang="en-US">The increase (decrease) during the period in the carrying value of fair value of the preferred investment options.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IncreaseInTheFairValueOfThePreferredInvestmentOptions" xlink:to="onco_IncreaseInTheFairValueOfThePreferredInvestmentOptions_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_InitialPaymentAmount_lbl0" xml:lang="en-US">The amount of initial payment amount.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_InitialPaymentAmount" xlink:to="onco_InitialPaymentAmount_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_InitialPublicOfferingShares_lbl0" xml:lang="en-US">Number of shares issued initial public offering of shares.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_InitialPublicOfferingShares" xlink:to="onco_InitialPublicOfferingShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_InventoryFairValue_lbl0" xml:lang="en-US">The amount of inventory fair value.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_InventoryFairValue" xlink:to="onco_InventoryFairValue_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_IssuanceOfCommonStockAndWarrantsInAprilPrivatePlacementNet_lbl0" xml:lang="en-US">Issuance of common stock and warrants in April private placement, net.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfCommonStockAndWarrantsInAprilPrivatePlacementNet" xlink:to="onco_IssuanceOfCommonStockAndWarrantsInAprilPrivatePlacementNet_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_IssuanceOfCommonStockAndWarrantsInPrivatePlacementNet_lbl0" xml:lang="en-US">Issuance of common stock and warrants in private placement, net.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfCommonStockAndWarrantsInPrivatePlacementNet" xlink:to="onco_IssuanceOfCommonStockAndWarrantsInPrivatePlacementNet_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_IssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptions_lbl0" xml:lang="en-US">Issuance of common stock from exercise of preferred investment options.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptions" xlink:to="onco_IssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptions_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_IssuanceOfCommonStockInInitialPublicOfferingNet_lbl0" xml:lang="en-US">Issuance of common stock in initial public offering, net.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfCommonStockInInitialPublicOfferingNet" xlink:to="onco_IssuanceOfCommonStockInInitialPublicOfferingNet_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_IssuanceOfRestrictedStock_lbl0" xml:lang="en-US">The number of shares issued in Issuance of restricted stock&#xd;
 exchange for the original debt being converted in a noncash (or part noncash) transaction. &quot;Part noncash&quot; refers to that portion of the transaction not resulting in cash receipts or payments in the period.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfRestrictedStock" xlink:to="onco_IssuanceOfRestrictedStock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_LicenseAgreement_lbl0" xml:lang="en-US">License agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_LicenseAgreement" xlink:to="onco_LicenseAgreement_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_LicensedProductsPlusMilestonePaymentsDescription_lbl0" xml:lang="en-US">Description of licensed products plus milestone payments.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_LicensedProductsPlusMilestonePaymentsDescription" xlink:to="onco_LicensedProductsPlusMilestonePaymentsDescription_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_MiscellaneousExpenses_lbl0" xml:lang="en-US">The amount of miscellaneous expenses.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_MiscellaneousExpenses" xlink:to="onco_MiscellaneousExpenses_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_NettingProceeds_lbl0" xml:lang="en-US">Represent the amount of netting proceeds.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_NettingProceeds" xlink:to="onco_NettingProceeds_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_NotesPayableNetOfDebtDiscount_lbl0" xml:lang="en-US">Notes payable, net of debt discount.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_NotesPayableNetOfDebtDiscount" xlink:to="onco_NotesPayableNetOfDebtDiscount_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_NumberOfShares_lbl0" xml:lang="en-US">Number of shares.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_NumberOfShares" xlink:to="onco_NumberOfShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_OtherComprehensiveIncomeLossForeignCurrencyTranslationsAdjustmentTax_lbl0" xml:lang="en-US">Foreign currency translation adjustment.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_OtherComprehensiveIncomeLossForeignCurrencyTranslationsAdjustmentTax" xlink:to="onco_OtherComprehensiveIncomeLossForeignCurrencyTranslationsAdjustmentTax_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PayableAverageDiscountRatePercentage_lbl0" xml:lang="en-US">The percentage of payable average discount rate.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PayableAverageDiscountRatePercentage" xlink:to="onco_PayableAverageDiscountRatePercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PaymentOfAccruedBonusThroughRelatedPartyReceivable_lbl0" xml:lang="en-US">Payment of accrued bonus through related party receivable.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PaymentOfAccruedBonusThroughRelatedPartyReceivable" xlink:to="onco_PaymentOfAccruedBonusThroughRelatedPartyReceivable_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_Payments_lbl0" xml:lang="en-US">The amount of payments.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_Payments" xlink:to="onco_Payments_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PaymentsForPurchaseOfTreasuryShares_lbl0" xml:lang="en-US">Payments for purchase of treasury stock.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PaymentsForPurchaseOfTreasuryShares" xlink:to="onco_PaymentsForPurchaseOfTreasuryShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PercentageOfCommonStockShares_lbl0" xml:lang="en-US">Percentage of Common Stock Shares.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfCommonStockShares" xlink:to="onco_PercentageOfCommonStockShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PercentageOfConsiderationReceived_lbl0" xml:lang="en-US">Percentage of consideration received.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfConsiderationReceived" xlink:to="onco_PercentageOfConsiderationReceived_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PercentageOfCumulativeDividends_lbl0" xml:lang="en-US">Percentage of cumulative dividends.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfCumulativeDividends" xlink:to="onco_PercentageOfCumulativeDividends_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PercentageOfGrossProceeds_lbl0" xml:lang="en-US">Percentage of gross proceeds.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfGrossProceeds" xlink:to="onco_PercentageOfGrossProceeds_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PercentageOfIssuedOfCommonStock_lbl0" xml:lang="en-US">Percentage of issued of common stock.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfIssuedOfCommonStock" xlink:to="onco_PercentageOfIssuedOfCommonStock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PercentageOfOriginalIssuePrice_lbl0" xml:lang="en-US">Percentage of Original Issue Price.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfOriginalIssuePrice" xlink:to="onco_PercentageOfOriginalIssuePrice_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PercentageOfOutstandingOfCommonStock_lbl0" xml:lang="en-US">Percentage of outstanding of common stock.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfOutstandingOfCommonStock" xlink:to="onco_PercentageOfOutstandingOfCommonStock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PercentageOfSubscription_lbl0" xml:lang="en-US">Percentage of subscription .</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfSubscription" xlink:to="onco_PercentageOfSubscription_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PercentageOfUnderwritingDiscount_lbl0" xml:lang="en-US">Percentage of underwriting discount.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfUnderwritingDiscount" xlink:to="onco_PercentageOfUnderwritingDiscount_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PlacementAgentFeeAndManagementFeePercentage_lbl0" xml:lang="en-US">Percentage of placement agent fee and management fee.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PlacementAgentFeeAndManagementFeePercentage" xlink:to="onco_PlacementAgentFeeAndManagementFeePercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PrefundedWarrantsExercised_lbl0" xml:lang="en-US">Number of prefunded share warrants exercised during the current period.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PrefundedWarrantsExercised" xlink:to="onco_PrefundedWarrantsExercised_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PrepaidProfessionalFees_lbl0" xml:lang="en-US">Prepaid professional fees.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PrepaidProfessionalFees" xlink:to="onco_PrepaidProfessionalFees_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PrepaidsResearchAndDevelopment_lbl0" xml:lang="en-US">Amount of other research and development expense.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PrepaidsResearchAndDevelopment" xlink:to="onco_PrepaidsResearchAndDevelopment_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PublicOfPerShare_lbl0" xml:lang="en-US">The share of public of per share.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PublicOfPerShare" xlink:to="onco_PublicOfPerShare_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PurchaseOfTreasuryShares_lbl0" xml:lang="en-US">Purchase of treasury shares.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PurchaseOfTreasuryShares" xlink:to="onco_PurchaseOfTreasuryShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_PurchaseOfTreasurySharesinShares_lbl0" xml:lang="en-US">The number of shares purchase of treasury shares.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PurchaseOfTreasurySharesinShares" xlink:to="onco_PurchaseOfTreasurySharesinShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_RealEstateInvestmentsRate_lbl0" xml:lang="en-US">Real estate investments rate.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RealEstateInvestmentsRate" xlink:to="onco_RealEstateInvestmentsRate_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ReceivableFromRelatedParties1_lbl0" xml:lang="en-US">The amount of receivables from related parties.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ReceivableFromRelatedParties1" xlink:to="onco_ReceivableFromRelatedParties1_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ReclassificationToEquity_lbl0" xml:lang="en-US">The amount represents the reclassification to equity.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ReclassificationToEquity" xlink:to="onco_ReclassificationToEquity_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_RecognitionOfContingentWarrantLiabilityUponIssuanceOfCommonStockInPrivatePlacement_lbl0" xml:lang="en-US">Recognition of contingent warrant liability upon issuance of common stock in private placement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RecognitionOfContingentWarrantLiabilityUponIssuanceOfCommonStockInPrivatePlacement" xlink:to="onco_RecognitionOfContingentWarrantLiabilityUponIssuanceOfCommonStockInPrivatePlacement_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_RestrictedSharesGrantedVestPercentage_lbl0" xml:lang="en-US">Restricted shares granted vest percentage.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RestrictedSharesGrantedVestPercentage" xlink:to="onco_RestrictedSharesGrantedVestPercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_RestrictedStockForfeitures_lbl0" xml:lang="en-US">Restricted stock forfeitures.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RestrictedStockForfeitures" xlink:to="onco_RestrictedStockForfeitures_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_RevenueRate_lbl0" xml:lang="en-US">Revenue rate.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RevenueRate" xlink:to="onco_RevenueRate_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_RoyaltiesPercentage_lbl0" xml:lang="en-US">Royalties percentage.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltiesPercentage" xlink:to="onco_RoyaltiesPercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_RoyaltyNetSalesPercentage_lbl0" xml:lang="en-US">Percentage of royalty net sales.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltyNetSalesPercentage" xlink:to="onco_RoyaltyNetSalesPercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_RoyaltyRate_lbl0" xml:lang="en-US">Percentage of royalty.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltyRate" xlink:to="onco_RoyaltyRate_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_RoyaltyRates_lbl0" xml:lang="en-US">Percentage of royalty rates.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltyRates" xlink:to="onco_RoyaltyRates_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_RoyaltySalesPercentage_lbl0" xml:lang="en-US">percentage of royalty sales percentage.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltySalesPercentage" xlink:to="onco_RoyaltySalesPercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_SaleOfUnits_lbl0" xml:lang="en-US">Sale of units.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SaleOfUnits" xlink:to="onco_SaleOfUnits_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_SalesPaymentsAmount_lbl0" xml:lang="en-US">The amount of sales payments amount.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SalesPaymentsAmount" xlink:to="onco_SalesPaymentsAmount_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ScheduleOfAccompanyingConsolidatedBalanceSheetTableTextBlock_lbl0" xml:lang="en-US">Disclosure of accompanying consolidated balance sheet.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfAccompanyingConsolidatedBalanceSheetTableTextBlock" xlink:to="onco_ScheduleOfAccompanyingConsolidatedBalanceSheetTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ScheduleOfFairValueOfOptionsGrantedIn2023And2022TableTextBlock_lbl0" xml:lang="en-US">Schedule of Fair Value of Options Granted in 2023 And 2022.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfFairValueOfOptionsGrantedIn2023And2022TableTextBlock" xlink:to="onco_ScheduleOfFairValueOfOptionsGrantedIn2023And2022TableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ScheduleOfValuationOfTheContingentWarrantLiabilityTableTextBlock_lbl0" xml:lang="en-US">Schedule of Valuation of the Contingent Warrant Liability.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfValuationOfTheContingentWarrantLiabilityTableTextBlock" xlink:to="onco_ScheduleOfValuationOfTheContingentWarrantLiabilityTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_SeverancePayment_lbl0" xml:lang="en-US">The amount of severance payment.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SeverancePayment" xlink:to="onco_SeverancePayment_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueForfeitedCancelled_lbl0" xml:lang="en-US">The value for share based compensation payment intrinsic value forfeited.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueForfeitedCancelled" xlink:to="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueForfeitedCancelled_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueGranted_lbl0" xml:lang="en-US">Share based compensation payment arrangementintrinsic value granted.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueGranted" xlink:to="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueGranted_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_SharesOfCommonStockIssued_lbl0" xml:lang="en-US">Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm&apos;s shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SharesOfCommonStockIssued" xlink:to="onco_SharesOfCommonStockIssued_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_SharesOfCommonStockRate_lbl0" xml:lang="en-US">Shares of common stock rate.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SharesOfCommonStockRate" xlink:to="onco_SharesOfCommonStockRate_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_SignificantAgreementsTextBlock_lbl0" xml:lang="en-US">The entire disclosure for significant agreements.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SignificantAgreementsTextBlock" xlink:to="onco_SignificantAgreementsTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodSharesAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction_lbl0" xml:lang="en-US">Assumption of stock-based compensation plan awards in connection with PMX Transaction.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodSharesAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction" xlink:to="onco_StockIssuedDuringPeriodSharesAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction_lbl1" xml:lang="en-US">Issuance of common stock and Series B Preferred Stock in connection with PMX Transaction.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction" xlink:to="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrants_lbl0" xml:lang="en-US">Number of common stock and warrants issued during the period.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrants" xlink:to="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrants_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrantsInAugustPrivatePlacementNet_lbl0" xml:lang="en-US">Number of common stock and warrants in August private placement issued during the period.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrantsInAugustPrivatePlacementNet" xlink:to="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndWarrantsInAugustPrivatePlacementNet_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfSeriesAPreferredStockinShares_lbl0" xml:lang="en-US">Issuance of series A preferred stock.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodSharesIssuanceOfSeriesAPreferredStockinShares" xlink:to="onco_StockIssuedDuringPeriodSharesIssuanceOfSeriesAPreferredStockinShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodValueAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction_lbl0" xml:lang="en-US">Assumption of stock-based compensation plan awards in connection with PMX Transaction.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction" xlink:to="onco_StockIssuedDuringPeriodValueAssumptionOfStockbasedCompensationPlanAwardsInConnectionWithPMXTransaction_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction_lbl0" xml:lang="en-US">Issuance of common stock and Series B Preferred Stock in connection with PMX Transaction.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction" xlink:to="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptionsinShares_lbl0" xml:lang="en-US">Issuance of common stock from exercise of preferred investment options.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptionsinShares" xlink:to="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptionsinShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceOfSeriesAPreferredStock_lbl0" xml:lang="en-US">Issuance of series A preferred stock.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueIssuanceOfSeriesAPreferredStock" xlink:to="onco_StockIssuedDuringPeriodValueIssuanceOfSeriesAPreferredStock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceofCommonStockandWarrantsinPrivatePlacement_lbl0" xml:lang="en-US">Issuance of common stock and warrants in private placement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueIssuanceofCommonStockandWarrantsinPrivatePlacement" xlink:to="onco_StockIssuedDuringPeriodValueIssuanceofCommonStockandWarrantsinPrivatePlacement_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodValueOfChangesInPensionBenefitObligation_lbl0" xml:lang="en-US">Amount of  changes in pension benefit obligation.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueOfChangesInPensionBenefitObligation" xlink:to="onco_StockIssuedDuringPeriodValueOfChangesInPensionBenefitObligation_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_StockIssuedDuringPeriodValueOfssuanceOfCommonStockAndWarrants_lbl0" xml:lang="en-US">Amount of issuance of common stock and warrants.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueOfssuanceOfCommonStockAndWarrants" xlink:to="onco_StockIssuedDuringPeriodValueOfssuanceOfCommonStockAndWarrants_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_SubscriptionAgreementDisclosureTextBlock_lbl0" xml:lang="en-US">The entire disclosure for subscription agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SubscriptionAgreementDisclosureTextBlock" xlink:to="onco_SubscriptionAgreementDisclosureTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_SubscriptionAgreementLiabilityNoncurrent_lbl0" xml:lang="en-US">Subscription agreement liability.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SubscriptionAgreementLiabilityNoncurrent" xlink:to="onco_SubscriptionAgreementLiabilityNoncurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_SubscriptionAgreementPMXInvestorPercentage_lbl0" xml:lang="en-US">Subscription agreement PMX investor percentage.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SubscriptionAgreementPMXInvestorPercentage" xlink:to="onco_SubscriptionAgreementPMXInvestorPercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_TreasuryStockPolicyPolicyTextBlock_lbl0" xml:lang="en-US">Disclosure of accounting policy for treasury stock.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_TreasuryStockPolicyPolicyTextBlock" xlink:to="onco_TreasuryStockPolicyPolicyTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_VotingInterestPercentage_lbl0" xml:lang="en-US">Voting interest percentage.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_VotingInterestPercentage" xlink:to="onco_VotingInterestPercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_WarrantsIssuableUnderProvisionShares_lbl0" xml:lang="en-US">Number of share warrants issuable under provision.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WarrantsIssuableUnderProvisionShares" xlink:to="onco_WarrantsIssuableUnderProvisionShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_WarrantsIssuedForSettlementOfContingentWarrants_lbl1" xml:lang="en-US">Warrants issued for settlement of contingent warrants.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WarrantsIssuedForSettlementOfContingentWarrants" xlink:to="onco_WarrantsIssuedForSettlementOfContingentWarrants_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_WeightedAverageDiscountRate_lbl0" xml:lang="en-US">Weighted average discount rate.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WeightedAverageDiscountRate" xlink:to="onco_WeightedAverageDiscountRate_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_WeightedAverageDiscountRateThereafter_lbl0" xml:lang="en-US">Percentage of minimum average discount rate there after.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WeightedAverageDiscountRateThereafter" xlink:to="onco_WeightedAverageDiscountRateThereafter_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:label="onco_WorkingCapitalDeficit_lbl0" xml:lang="en-US">Working capital deficit.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WorkingCapitalDeficit" xlink:to="onco_WorkingCapitalDeficit_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_lbl1" xml:lang="en-US">benefit cost</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent" xlink:to="us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_AmendmentDescription_lbl0" xml:lang="en-US">Amendment Description</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_AmendmentDescription" xlink:to="dei_AmendmentDescription_lbl0"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_WraSerAPAMember_lbl0" xml:lang="en-US">Wra Ser APAMember</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherOwnershipInterestsOfferingCosts_lbl0" xml:lang="en-US">Other Ownership Interests, Offering Costs</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DevelopedTechnologyRightsMember_lbl2" xml:lang="en-US">Developed Technology Rights [Member]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_lbl0" xml:lang="en-US">Net Cash Provided by (Used in) Operating Activities [Abstract]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl0" xml:lang="en-US">Share-Based Payment Arrangement, Expense</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalOther_lbl0" xml:lang="en-US">Adjustments to Additional Paid in Capital, Other</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptionsinShares_lbl1" xml:lang="en-US">Stock Issued During Period Value Issuance Of Common Stock From Exercise Of Preferred Investment Optionsin Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptionsinShares" xlink:to="onco_StockIssuedDuringPeriodValueIssuanceOfCommonStockFromExerciseOfPreferredInvestmentOptionsinShares_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_lbl0" xml:lang="en-US">Net Cash Provided by (Used in) Financing Activities [Abstract]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesCustomerRelationships_lbl1" xml:lang="en-US">Business Combination Recognized Identifiable Assets Acquired And Liabilities Customer Relationships</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesCustomerRelationships" xlink:to="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesCustomerRelationships_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SeriesBPreferredStockMember_lbl1" xml:lang="en-US">Series B Preferred Stock [Member]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxAssetsNetAbstract_lbl0" xml:lang="en-US">Deferred Tax Assets, Net [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsNetAbstract" xlink:to="us-gaap_DeferredTaxAssetsNetAbstract_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtConversionConvertedInstrumentAmount1_lbl0" xml:lang="en-US">Debt Conversion, Converted Instrument, Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtConversionConvertedInstrumentAmount1" xlink:to="us-gaap_DebtConversionConvertedInstrumentAmount1_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommonUnitIssued_lbl0" xml:lang="en-US">Common Unit, Issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonUnitIssued" xlink:to="us-gaap_CommonUnitIssued_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_CancelledPreferredInvestmentOptionsShares_lbl1" xml:lang="en-US">Cancelled Preferred Investment Options Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CancelledPreferredInvestmentOptionsShares" xlink:to="onco_CancelledPreferredInvestmentOptionsShares_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockholdersEquityAbstract_lbl0" xml:lang="en-US">Equity, Attributable to Parent [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_StockholdersEquityAbstract_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_TemporaryEquityParOrStatedValuePerShare_lbl0" xml:lang="en-US">Temporary Equity, Par or Stated Value Per Share</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquityParOrStatedValuePerShare" xlink:to="us-gaap_TemporaryEquityParOrStatedValuePerShare_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_lbl0" xml:lang="en-US">Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LiabilitiesFairValueAdjustment_lbl0" xml:lang="en-US">Liabilities, Fair Value Adjustment</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_lbl0" xml:lang="en-US">Business Acquisition, Transaction Costs</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AggregateNumberOfSharesPercenatge_lbl1" xml:lang="en-US">Aggregate Number Of Shares Percenatge</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateNumberOfSharesPercenatge" xlink:to="onco_AggregateNumberOfSharesPercenatge_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AugustWainwrightWarrantsMember_lbl0" xml:lang="en-US">August Wainwright Warrants Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AugustWainwrightWarrantsMember" xlink:to="onco_AugustWainwrightWarrantsMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockSharesAuthorized_lbl1" xml:lang="en-US">Preferred Stock, Shares Authorized</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesAuthorized" xlink:to="us-gaap_PreferredStockSharesAuthorized_lbl1"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ProteomedixMember_lbl0" xml:lang="en-US">Proteomedix Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ResearchAndDevelopmentMember_lbl0" xml:lang="en-US">Research And Development Member</label>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionDescriptionOfAcquiredEntity" xlink:to="us-gaap_BusinessAcquisitionDescriptionOfAcquiredEntity_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_HCWainwrightCoLLCMember_lbl0" xml:lang="en-US">HCWainwright Co LLCMember</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_HCWainwrightCoLLCMember" xlink:to="onco_HCWainwrightCoLLCMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SignificantAccountingPoliciesTextBlock_lbl0" xml:lang="en-US">Significant Accounting Policies [Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SignificantAccountingPoliciesTextBlock" xlink:to="us-gaap_SignificantAccountingPoliciesTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_TwoThousandNinteenEquityIncentivePlanMember_lbl0" xml:lang="en-US">Two Thousand Ninteen Equity Incentive Plan Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_TwoThousandNinteenEquityIncentivePlanMember" xlink:to="onco_TwoThousandNinteenEquityIncentivePlanMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommitmentsAndContingenciesPolicyTextBlock_lbl0" xml:lang="en-US">Commitments and Contingencies, Policy [Policy Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommitmentsAndContingenciesPolicyTextBlock" xlink:to="us-gaap_CommitmentsAndContingenciesPolicyTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InvestmentOwnedAtCost_lbl0" xml:lang="en-US">Investment Owned, Cost</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InvestmentOwnedAtCost" xlink:to="us-gaap_InvestmentOwnedAtCost_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_lbl0" xml:lang="en-US">Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock" xlink:to="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntityIncorporationStateCountryCode_lbl0" xml:lang="en-US">Entity Incorporation, State or Country Code</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityIncorporationStateCountryCode" xlink:to="dei_EntityIncorporationStateCountryCode_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_lbl1" xml:lang="en-US">Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:to="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_EquitySecuritiesRate_lbl1" xml:lang="en-US">Equity Securities Rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_EquitySecuritiesRate" xlink:to="onco_EquitySecuritiesRate_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl0" xml:lang="en-US">Common Stock, Shares, Outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesOutstanding" xlink:to="us-gaap_CommonStockSharesOutstanding_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_MinimumMember_lbl1" xml:lang="en-US">Minimum [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MinimumMember" xlink:to="srt_MinimumMember_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfStockholdersEquityNoteWarrantsOrRightsTextBlock_lbl0" xml:lang="en-US">Schedule of Stockholders&apos; Equity Note, Warrants or Rights [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfStockholdersEquityNoteWarrantsOrRightsTextBlock" xlink:to="us-gaap_ScheduleOfStockholdersEquityNoteWarrantsOrRightsTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ServicingLiabilityAtFairValueAmount_lbl0" xml:lang="en-US">Servicing Liability at Fair Value, Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ServicingLiabilityAtFairValueAmount" xlink:to="us-gaap_ServicingLiabilityAtFairValueAmount_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxReconciliationTaxCreditsResearch_lbl0" xml:lang="en-US">Effective Income Tax Rate Reconciliation, Tax Credit, Research, Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationTaxCreditsResearch" xlink:to="us-gaap_IncomeTaxReconciliationTaxCreditsResearch_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PlacementAgentFeeAndManagementFeePercentage_lbl1" xml:lang="en-US">Placement Agent Fee And Management Fee Percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PlacementAgentFeeAndManagementFeePercentage" xlink:to="onco_PlacementAgentFeeAndManagementFeePercentage_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ConcentrationRiskCreditRisk_lbl0" xml:lang="en-US">Concentration Risk, Credit Risk, Policy [Policy Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskCreditRisk" xlink:to="us-gaap_ConcentrationRiskCreditRisk_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_lbl0" xml:lang="en-US">Impairment of Intangible Assets, Indefinite-Lived (Excluding Goodwill)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill" xlink:to="us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AdditionalPaidInCapitalMember_lbl0" xml:lang="en-US">Additional Paid-in Capital [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdditionalPaidInCapitalMember" xlink:to="us-gaap_AdditionalPaidInCapitalMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingExpensesAbstract_lbl0" xml:lang="en-US">Operating Expenses [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_OperatingExpensesAbstract_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl0" xml:lang="en-US">Payments to Acquire Property, Plant, and Equipment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_OnconetixMember_lbl0" xml:lang="en-US">Onconetix Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_OnconetixMember" xlink:to="onco_OnconetixMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_SeriesSeedPreferredStockMember_lbl1" xml:lang="en-US">Series Seed Preferred Stock Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SeriesSeedPreferredStockMember" xlink:to="onco_SeriesSeedPreferredStockMember_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl0" xml:lang="en-US">Finite-Lived Intangible Asset, Expected Amortization, Year One</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PurchaseOfTreasurySharesinShares_lbl1" xml:lang="en-US">Purchase Of Treasury Sharesin Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PurchaseOfTreasurySharesinShares" xlink:to="onco_PurchaseOfTreasurySharesinShares_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PurchaseOfTreasuryShares_lbl1" xml:lang="en-US">Purchase Of Treasury Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PurchaseOfTreasuryShares" xlink:to="onco_PurchaseOfTreasuryShares_lbl1"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfAccumulatedComprehensiveLossAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfAccumulatedComprehensiveLossAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfAccumulatedComprehensiveLossAbstract_lbl" xml:lang="en-US">Schedule Of Accumulated Comprehensive Loss Abstract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfAccumulatedComprehensiveLossAbstract" xlink:to="onco_ScheduleOfAccumulatedComprehensiveLossAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_August2024Member_lbl0" xml:lang="en-US">August2024 Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_August2024Member" xlink:to="onco_August2024Member_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockSharesOutstanding_lbl1" xml:lang="en-US">Preferred Stock, Shares Outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesOutstanding" xlink:to="us-gaap_PreferredStockSharesOutstanding_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_WraSerMSAMember_lbl0" xml:lang="en-US">Wra Ser MSAMember</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WraSerMSAMember" xlink:to="onco_WraSerMSAMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AlternativeInvestmentsRate_lbl1" xml:lang="en-US">Alternative Investments Rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AlternativeInvestmentsRate" xlink:to="onco_AlternativeInvestmentsRate_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueOptionQuantitativeDisclosuresTextBlock_lbl0" xml:lang="en-US">Fair Value Option, Disclosures [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueOptionQuantitativeDisclosuresTextBlock" xlink:to="us-gaap_FairValueOptionQuantitativeDisclosuresTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxPolicyTextBlock_lbl0" xml:lang="en-US">Income Tax, Policy [Policy Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxPolicyTextBlock" xlink:to="us-gaap_IncomeTaxPolicyTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCosts_lbl0" xml:lang="en-US">Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCosts" xlink:to="us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCosts_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_Goodwill_lbl2" xml:lang="en-US">Goodwill</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Goodwill" xlink:to="us-gaap_Goodwill_lbl2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetImpairmentCharges_lbl0" xml:lang="en-US">Asset Impairment Charges</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetImpairmentCharges" xlink:to="us-gaap_AssetImpairmentCharges_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_TradeAndOtherAccountsReceivablePolicy_lbl0" xml:lang="en-US">Accounts Receivable [Policy Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TradeAndOtherAccountsReceivablePolicy" xlink:to="us-gaap_TradeAndOtherAccountsReceivablePolicy_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfAccompanyingConsolidatedBalanceSheetTableTextBlock_lbl1" xml:lang="en-US">Schedule Of Accompanying Consolidated Balance Sheet Table Text Block</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfAccompanyingConsolidatedBalanceSheetTableTextBlock" xlink:to="onco_ScheduleOfAccompanyingConsolidatedBalanceSheetTableTextBlock_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharesIssued_lbl1" xml:lang="en-US">Shares, Issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharesIssued" xlink:to="us-gaap_SharesIssued_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl0" xml:lang="en-US">Retained Earnings (Accumulated Deficit)</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockMember_lbl1" xml:lang="en-US">Preferred Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockMember" xlink:to="us-gaap_PreferredStockMember_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_LaboratorCorporationOfAmericaMember_lbl0" xml:lang="en-US">Laborator Corporation Of America Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_LaboratorCorporationOfAmericaMember" xlink:to="onco_LaboratorCorporationOfAmericaMember_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfValuationOfTheContingentWarrantLiabilityAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfValuationOfTheContingentWarrantLiabilityAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfValuationOfTheContingentWarrantLiabilityAbstract_lbl" xml:lang="en-US">Schedule Of Valuation Of The Contingent Warrant Liability Abstract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfValuationOfTheContingentWarrantLiabilityAbstract" xlink:to="onco_ScheduleOfValuationOfTheContingentWarrantLiabilityAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_SeriesAConvertiblePreferredStockMember_lbl1" xml:lang="en-US">Series AConvertible Preferred Stock Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SeriesAConvertiblePreferredStockMember" xlink:to="onco_SeriesAConvertiblePreferredStockMember_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AssetsRecognizedMember_lbl0" xml:lang="en-US">Assets Recognized Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl1" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_SeverancePayment_lbl1" xml:lang="en-US">Severance Payment</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PaymentsToAcquireOtherProductiveAssets_lbl0" xml:lang="en-US">Payments to Acquire Other Productive Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquireOtherProductiveAssets" xlink:to="us-gaap_PaymentsToAcquireOtherProductiveAssets_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueForfeitedCancelled_lbl1" xml:lang="en-US">Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value Forfeited Cancelled</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueForfeitedCancelled" xlink:to="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueForfeitedCancelled_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProductLiabilityContingencyThirdPartyRecoveryPercentage_lbl0" xml:lang="en-US">Product Liability Contingency, Third-Party Recovery, Percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProductLiabilityContingencyThirdPartyRecoveryPercentage" xlink:to="us-gaap_ProductLiabilityContingencyThirdPartyRecoveryPercentage_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfNonvestedRestrictedStockUnitsActivityTableTextBlock_lbl0" xml:lang="en-US">Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfNonvestedRestrictedStockUnitsActivityTableTextBlock" xlink:to="us-gaap_ScheduleOfNonvestedRestrictedStockUnitsActivityTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax_lbl1" xml:lang="en-US">Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax" xlink:to="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_RecognitionOfContingentWarrantLiabilityUponIssuanceOfCommonStockInPrivatePlacement_lbl1" xml:lang="en-US">Recognition Of Contingent Warrant Liability Upon Issuance Of Common Stock In Private Placement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RecognitionOfContingentWarrantLiabilityUponIssuanceOfCommonStockInPrivatePlacement" xlink:to="onco_RecognitionOfContingentWarrantLiabilityUponIssuanceOfCommonStockInPrivatePlacement_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_Exerciseofprefundedwarrants_lbl1" xml:lang="en-US">Exerciseofprefundedwarrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_Exerciseofprefundedwarrants" xlink:to="onco_Exerciseofprefundedwarrants_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_lbl0" xml:lang="en-US">Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" xlink:to="us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_lbl1" xml:lang="en-US">Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl1" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensation_lbl0" xml:lang="en-US">Share-Based Payment Arrangement, Noncash Expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensation" xlink:to="us-gaap_ShareBasedCompensation_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_lbl0" xml:lang="en-US">Finite-Lived Intangible Asset, Expected Amortization, after Year Five</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InterestPayableCurrentAndNoncurrent_lbl0" xml:lang="en-US">Interest Payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestPayableCurrentAndNoncurrent" xlink:to="us-gaap_InterestPayableCurrentAndNoncurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockOptionMember_lbl2" xml:lang="en-US">Equity Option [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockOptionMember" xlink:to="us-gaap_StockOptionMember_lbl2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPortionAttributableToParent_lbl0" xml:lang="en-US">Other Comprehensive (Income) Loss, Defined Benefit Plan, before Tax, after Reclassification Adjustment, Attributable to Parent</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPortionAttributableToParent" xlink:to="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPortionAttributableToParent_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfAssetsAcquiredAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfAssetsAcquiredAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfAssetsAcquiredAbstract_lbl" xml:lang="en-US">Schedule Of Assets Acquired Abstract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfAssetsAcquiredAbstract" xlink:to="onco_ScheduleOfAssetsAcquiredAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl1" xml:lang="en-US">Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl0" xml:lang="en-US">Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ResearchAndDevelopmentExpensePolicy_lbl0" xml:lang="en-US">Research and Development Expense, Policy [Policy Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentExpensePolicy" xlink:to="us-gaap_ResearchAndDevelopmentExpensePolicy_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredIncomeTaxLiabilities_lbl0" xml:lang="en-US">Deferred Tax Liabilities, Gross</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxLiabilities" xlink:to="us-gaap_DeferredIncomeTaxLiabilities_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_SubscriptionAgreementMember_lbl0" xml:lang="en-US">Subscription Agreement Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SubscriptionAgreementMember" xlink:to="onco_SubscriptionAgreementMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_lbl0" xml:lang="en-US">Business Combination, Consideration Transferred, Equity Interests Issued and Issuable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable" xlink:to="us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance_lbl0" xml:lang="en-US">Deferred Tax Assets, Valuation Allowance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsValuationAllowance" xlink:to="us-gaap_DeferredTaxAssetsValuationAllowance_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RepaymentsOfNotesPayable_lbl0" xml:lang="en-US">Repayments of Notes Payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RepaymentsOfNotesPayable" xlink:to="us-gaap_RepaymentsOfNotesPayable_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AmortizationOfDebtDiscountPremium_lbl0" xml:lang="en-US">Amortization of Debt Discount (Premium)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AmortizationOfDebtDiscountPremium" xlink:to="us-gaap_AmortizationOfDebtDiscountPremium_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable_lbl0" xml:lang="en-US">Increase (Decrease) in Accounts Receivable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:to="us-gaap_IncreaseDecreaseInAccountsReceivable_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfIntangibleAssetsAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfIntangibleAssetsAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfIntangibleAssetsAbstract_lbl" xml:lang="en-US">Schedule Of Intangible Assets Abstract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfIntangibleAssetsAbstract" xlink:to="onco_ScheduleOfIntangibleAssetsAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl2" xml:lang="en-US">Debt Instrument, Interest Rate, Effective Percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:to="us-gaap_DebtInstrumentInterestRateEffectivePercentage_lbl2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShortTermLeasePayments_lbl0" xml:lang="en-US">Short-Term Lease Payments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermLeasePayments" xlink:to="us-gaap_ShortTermLeasePayments_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl1" xml:lang="en-US">Research and Development Expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentExpense" xlink:to="us-gaap_ResearchAndDevelopmentExpense_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_LicensedProductsPlusMilestonePaymentsDescription_lbl1" xml:lang="en-US">Licensed Products Plus Milestone Payments Description</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_LicensedProductsPlusMilestonePaymentsDescription" xlink:to="onco_LicensedProductsPlusMilestonePaymentsDescription_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_LiabilitiesAbstract0_lbl0" xml:lang="en-US">Liabilities Abstract0</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_LiabilitiesAbstract0" xlink:to="onco_LiabilitiesAbstract0_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementOfStockholdersEquityAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementOfStockholdersEquityAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StatementOfStockholdersEquityAbstract_lbl" xml:lang="en-US">Statement of Stockholders&apos; Equity [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StatementOfStockholdersEquityAbstract" xlink:to="us-gaap_StatementOfStockholdersEquityAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_DebtSecuritiesAndCash_lbl1" xml:lang="en-US">Debt Securities And Cash</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DebtSecuritiesAndCash" xlink:to="onco_DebtSecuritiesAndCash_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl0" xml:lang="en-US">Stock Issued During Period, Value, New Issues</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:to="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessAcquisitionsProFormaRevenue_lbl0" xml:lang="en-US">Business Acquisition, Pro Forma Revenue</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:to="us-gaap_BusinessAcquisitionsProFormaRevenue_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommitmentsAndContingencies_lbl0" xml:lang="en-US">Commitments and Contingencies</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommitmentsAndContingencies" xlink:to="us-gaap_CommitmentsAndContingencies_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PensionExpense_lbl0" xml:lang="en-US">Pension Cost (Reversal of Cost)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PensionExpense" xlink:to="us-gaap_PensionExpense_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_lbl0" xml:lang="en-US">Finite-Lived Intangible Asset, Expected Amortization, Year Five</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SeriesAPreferredStockMember_lbl1" xml:lang="en-US">Series A Preferred Stock [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SeriesAPreferredStockMember" xlink:to="us-gaap_SeriesAPreferredStockMember_lbl1"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ENTADFIMember_lbl0" xml:lang="en-US">ENTADFIMember</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromIssuanceOfWarrants_lbl0" xml:lang="en-US">Proceeds from Issuance of Warrants</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ExerciseOfPrefundedWarrants_lbl1" xml:lang="en-US">Exercise Of Prefunded Warrants</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligation_lbl1" xml:lang="en-US">Defined Benefit Plan, Benefit Obligation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanBenefitObligation" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligation_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PrepaidsResearchAndDevelopment_lbl1" xml:lang="en-US">Prepaids Research And Development</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PrepaidsResearchAndDevelopment" xlink:to="onco_PrepaidsResearchAndDevelopment_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationConsiderationTransferredOther1_lbl0" xml:lang="en-US">Business Combination, Consideration Transferred, Other</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationConsiderationTransferredOther1" xlink:to="us-gaap_BusinessCombinationConsiderationTransferredOther1_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl0" xml:lang="en-US">Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Continuing Operations</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:to="us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryRawMaterials_lbl0" xml:lang="en-US">Inventory, Raw Materials, Gross</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryRawMaterials" xlink:to="us-gaap_InventoryRawMaterials_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtInstrumentFeeAmount_lbl0" xml:lang="en-US">Debt Instrument, Fee Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentFeeAmount" xlink:to="us-gaap_DebtInstrumentFeeAmount_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_TaxesAndLicenses_lbl0" xml:lang="en-US">Taxes and Licenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TaxesAndLicenses" xlink:to="us-gaap_TaxesAndLicenses_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PercentageOfOutstandingOfCommonStock_lbl1" xml:lang="en-US">Percentage Of Outstanding Of Common Stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfOutstandingOfCommonStock" xlink:to="onco_PercentageOfOutstandingOfCommonStock_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProfitLoss_lbl1" xml:lang="en-US">Net Income (Loss), Including Portion Attributable to Noncontrolling Interest</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProfitLoss" xlink:to="us-gaap_ProfitLoss_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_CincinnatiChildrensHospitalMedicalCenterMember_lbl0" xml:lang="en-US">Cincinnati Childrens Hospital Medical Center Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CincinnatiChildrensHospitalMedicalCenterMember" xlink:to="onco_CincinnatiChildrensHospitalMedicalCenterMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_lbl0" xml:lang="en-US">Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1" xlink:to="us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PercentageOfUnderwritingDiscount_lbl1" xml:lang="en-US">Percentage Of Underwriting Discount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfUnderwritingDiscount" xlink:to="onco_PercentageOfUnderwritingDiscount_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ImpairmentOfIntangibleAssetExcludingGoodwill_lbl1" xml:lang="en-US">Impairment Of Intangible Asset Excluding Goodwill</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ImpairmentOfIntangibleAssetExcludingGoodwill" xlink:to="onco_ImpairmentOfIntangibleAssetExcludingGoodwill_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IPOMember_lbl0" xml:lang="en-US">IPO [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IPOMember" xlink:to="us-gaap_IPOMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_lbl0" xml:lang="en-US">Defined Benefit Plan, Expected Future Benefit Payment, Year One</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SubsequentEventsTextBlock_lbl0" xml:lang="en-US">Subsequent Events [Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventsTextBlock" xlink:to="us-gaap_SubsequentEventsTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_RoyaltyRates_lbl1" xml:lang="en-US">Royalty Rates</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_lbl0" xml:lang="en-US">Convertible Preferred Stock, Shares Issued upon Conversion</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:to="us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PercentageOfCumulativeDividends_lbl1" xml:lang="en-US">Percentage Of Cumulative Dividends</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfCumulativeDividends" xlink:to="onco_PercentageOfCumulativeDividends_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountsPayableCurrentAndNoncurrent_lbl0" xml:lang="en-US">Accounts Payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableCurrentAndNoncurrent" xlink:to="us-gaap_AccountsPayableCurrentAndNoncurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AmortizationOfIntangibleAssets_lbl1" xml:lang="en-US">Amortization of Intangible Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AmortizationOfIntangibleAssets" xlink:to="us-gaap_AmortizationOfIntangibleAssets_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NumberOfOperatingSegments_lbl0" xml:lang="en-US">Number of Operating Segments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NumberOfOperatingSegments" xlink:to="us-gaap_NumberOfOperatingSegments_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_UseOfEstimates_lbl0" xml:lang="en-US">Use of Estimates, Policy [Policy Text Block]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanOtherChanges_lbl0" xml:lang="en-US">Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Other Change</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanOtherChanges" xlink:to="us-gaap_DefinedBenefitPlanOtherChanges_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncomeStatementAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeStatementAbstract_lbl" xml:lang="en-US">Income Statement [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_IncomeStatementAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_CostPlusPercentage_lbl1" xml:lang="en-US">Cost Plus Percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CostPlusPercentage" xlink:to="onco_CostPlusPercentage_lbl1"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfAssumptionsUsedInMonteCarloModelWhichUtilizesLevel3InputsAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfAssumptionsUsedInMonteCarloModelWhichUtilizesLevel3InputsAbstract"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperations_lbl0" xml:lang="en-US">Effective Income Tax Rate Reconciliation, Percent</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:to="us-gaap_EffectiveIncomeTaxRateContinuingOperations_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GoodwillTransfers_lbl0" xml:lang="en-US">Goodwill, Transfers</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillTransfers" xlink:to="us-gaap_GoodwillTransfers_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax_lbl0" xml:lang="en-US">Other Comprehensive Income (Loss), Net of Tax</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetOfTax_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherReceivables_lbl0" xml:lang="en-US">Other Receivables</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherReceivables" xlink:to="us-gaap_OtherReceivables_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ConversionOfStockAmountIssued1_lbl0" xml:lang="en-US">Conversion of Stock, Amount Issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConversionOfStockAmountIssued1" xlink:to="us-gaap_ConversionOfStockAmountIssued1_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IndefiniteLivedTradeNames_lbl0" xml:lang="en-US">Indefinite-Lived Trade Names</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IndefiniteLivedTradeNames" xlink:to="us-gaap_IndefiniteLivedTradeNames_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountsPayableCurrent_lbl0" xml:lang="en-US">Accounts Payable, Current</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableCurrent" xlink:to="us-gaap_AccountsPayableCurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NotesPayableCurrent_lbl0" xml:lang="en-US">Notes Payable, Current</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues_lbl0" xml:lang="en-US">Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockOptionExercisePriceIncrease_lbl0" xml:lang="en-US">Stock Option, Exercise Price, Increase</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LiabilitiesSubjectToCompromiseEarlyContractTerminationFees_lbl0" xml:lang="en-US">Liabilities Subject to Compromise, Early Contract Termination Fees</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities_lbl0" xml:lang="en-US">Net Cash Provided by (Used in) Financing Activities</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntityRegistrantName_lbl0" xml:lang="en-US">Entity Registrant Name</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_OUIAgreementMember_lbl0" xml:lang="en-US">OUIAgreement Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_WarrantMember_lbl1" xml:lang="en-US">Warrant [Member]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_VendorAgreementMember_lbl0" xml:lang="en-US">Vendor Agreement Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedContributionPlanEmployersMatchingContributionAnnualVestingPercentage_lbl0" xml:lang="en-US">Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage</label>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SellingGeneralAndAdministrativeExpensesMember" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpensesMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock_lbl0" xml:lang="en-US">Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl0" xml:lang="en-US">Liabilities, Current [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_LiabilitiesCurrentAbstract_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_RoyaltyNetSalesPercentage_lbl1" xml:lang="en-US">Royalty Net Sales Percentage</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherReceivablesNetCurrent_lbl1" xml:lang="en-US">Other Receivables, Net, Current</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AprilContingentWarrantsMember_lbl0" xml:lang="en-US">April Contingent Warrants Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DepreciationDepletionAndAmortization_lbl0" xml:lang="en-US">Depreciation, Depletion and Amortization</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetAcquisitionConsiderationTransferredTransactionCost_lbl0" xml:lang="en-US">Asset Acquisition, Consideration Transferred, Transaction Cost</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtInstrumentAnnualPrincipalPayment_lbl1" xml:lang="en-US">Debt Instrument, Annual Principal Payment</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LaborAndRelatedExpense_lbl0" xml:lang="en-US">Labor and Related Expense</label>
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    <loc xlink:type="locator" xlink:label="us-gaap_StatementOfCashFlowsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementOfCashFlowsAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StatementOfCashFlowsAbstract_lbl" xml:lang="en-US">Statement of Cash Flows [Abstract]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InterestExpense_lbl0" xml:lang="en-US">Interest Expense</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested, Number of Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl1" xml:lang="en-US">Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxDisclosureTextBlock_lbl0" xml:lang="en-US">Income Tax Disclosure [Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxDisclosureTextBlock" xlink:to="us-gaap_IncomeTaxDisclosureTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_FiniteLivedIntangibleAssetsAccumulatedAmortizationEffectOfCurrencyTranslation_lbl1" xml:lang="en-US">Finite Lived Intangible Assets Accumulated Amortization Effect Of Currency Translation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_FiniteLivedIntangibleAssetsAccumulatedAmortizationEffectOfCurrencyTranslation" xlink:to="onco_FiniteLivedIntangibleAssetsAccumulatedAmortizationEffectOfCurrencyTranslation_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_SubscriptionAgreementLiabilityNoncurrent_lbl1" xml:lang="en-US">Subscription Agreement Liability Noncurrent</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SubscriptionAgreementLiabilityNoncurrent" xlink:to="onco_SubscriptionAgreementLiabilityNoncurrent_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense_lbl2" xml:lang="en-US">Selling, General and Administrative Expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense_lbl2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PaymentOfAccruedBonusThroughRelatedPartyReceivable_lbl1" xml:lang="en-US">Payment Of Accrued Bonus Through Related Party Receivable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PaymentOfAccruedBonusThroughRelatedPartyReceivable" xlink:to="onco_PaymentOfAccruedBonusThroughRelatedPartyReceivable_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl0" xml:lang="en-US">Liabilities and Equity [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl2" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_lbl2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_RoyaltiesPercentage_lbl1" xml:lang="en-US">Royalties Percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltiesPercentage" xlink:to="onco_RoyaltiesPercentage_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ChangeInPensionBenefitObligation_lbl1" xml:lang="en-US">Change In Pension Benefit Obligation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ChangeInPensionBenefitObligation" xlink:to="onco_ChangeInPensionBenefitObligation_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_UnrecognizedTaxBenefits_lbl1" xml:lang="en-US">Unrecognized Tax Benefits</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnrecognizedTaxBenefits" xlink:to="us-gaap_UnrecognizedTaxBenefits_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_lbl0" xml:lang="en-US">Stock Issued During Period, Value, Stock Options Exercised</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:to="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_CommonStockIssuableUponConversionOfSeriesAPreferredStockMember_lbl0" xml:lang="en-US">Common Stock Issuable Upon Conversion Of Series APreferred Stock Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CommonStockIssuableUponConversionOfSeriesAPreferredStockMember" xlink:to="onco_CommonStockIssuableUponConversionOfSeriesAPreferredStockMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryWorkInProcess_lbl0" xml:lang="en-US">Inventory, Work in Process, Gross</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryWorkInProcess" xlink:to="us-gaap_InventoryWorkInProcess_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_RoyaltySalesPercentage_lbl1" xml:lang="en-US">Royalty Sales Percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_RoyaltySalesPercentage" xlink:to="onco_RoyaltySalesPercentage_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_DebtInstrumentDueDate_lbl1" xml:lang="en-US">Debt Instrument Due Date</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharesHeldInEmployeeStockOptionPlanAllocated_lbl0" xml:lang="en-US">Shares Held in Employee Stock Option Plan, Allocated</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharesHeldInEmployeeStockOptionPlanAllocated" xlink:to="us-gaap_SharesHeldInEmployeeStockOptionPlanAllocated_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_MilestonePaymentsMember_lbl0" xml:lang="en-US">Milestone Payments Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockOptionExercisePriceDecrease_lbl0" xml:lang="en-US">Stock Option, Exercise Price, Decrease</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_LicenseAgreement_lbl1" xml:lang="en-US">License Agreement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_LicenseAgreement" xlink:to="onco_LicenseAgreement_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherPrepaidExpenseCurrent_lbl0" xml:lang="en-US">Other Prepaid Expense, Current</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherPrepaidExpenseCurrent" xlink:to="us-gaap_OtherPrepaidExpenseCurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PercentageOfOriginalIssuePrice_lbl1" xml:lang="en-US">Percentage Of Original Issue Price</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherLiabilitiesCurrent_lbl0" xml:lang="en-US">Other Liabilities, Current</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GrossProfit_lbl0" xml:lang="en-US">Gross Profit</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_RegulatoryMilestonesMember_lbl0" xml:lang="en-US">Regulatory Milestones Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntityExTransitionPeriod_lbl0" xml:lang="en-US">Entity Ex Transition Period</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommonStockSharesSubscribedButUnissued_lbl0" xml:lang="en-US">Common Stock, Shares Subscribed but Unissued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesSubscribedButUnissued" xlink:to="us-gaap_CommonStockSharesSubscribedButUnissued_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl0" xml:lang="en-US">Liabilities and Equity</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfConsolidatedStatementsOfOperationsAndComprehensiveLossAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfConsolidatedStatementsOfOperationsAndComprehensiveLossAbstract"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueOfAssetsAcquired_lbl1" xml:lang="en-US">Fair Value of Assets Acquired</label>
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    <loc xlink:type="locator" xlink:label="onco_ScheduleOfComponentsOfNetPeriodicBenefitCostAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfComponentsOfNetPeriodicBenefitCostAbstract"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfComponentsOfNetPeriodicBenefitCostAbstract" xlink:to="onco_ScheduleOfComponentsOfNetPeriodicBenefitCostAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AggregatePurchaseShares_lbl2" xml:lang="en-US">Aggregate Purchase Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregatePurchaseShares" xlink:to="onco_AggregatePurchaseShares_lbl2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_FairValueConsiderationTransferredMember_lbl0" xml:lang="en-US">Fair Value Consideration Transferred Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_FairValueConsiderationTransferredMember" xlink:to="onco_FairValueConsiderationTransferredMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_IssuanceOfCommonStockInInitialPublicOfferingNet_lbl1" xml:lang="en-US">Issuance Of Common Stock In Initial Public Offering Net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfCommonStockInInitialPublicOfferingNet" xlink:to="onco_IssuanceOfCommonStockInInitialPublicOfferingNet_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_lbl0" xml:lang="en-US">Payments to Acquire Businesses, Net of Cash Acquired</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:to="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl0" xml:lang="en-US">Finite-Lived Intangible Asset, Expected Amortization, Year Four</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetAcquisitionContingentConsiderationTableTextBlock_lbl0" xml:lang="en-US">Asset Acquisition, Contingent Consideration [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetAcquisitionContingentConsiderationTableTextBlock" xlink:to="us-gaap_AssetAcquisitionContingentConsiderationTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_lbl0" xml:lang="en-US">Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant" xlink:to="us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetsCurrent_lbl0" xml:lang="en-US">Assets, Current</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_AssetsCurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_lbl0" xml:lang="en-US">Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssued1_lbl0" xml:lang="en-US">Stock Issued</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueOfFinancialInstrumentsPolicy_lbl0" xml:lang="en-US">Fair Value of Financial Instruments, Policy [Policy Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:to="us-gaap_FairValueOfFinancialInstrumentsPolicy_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommonStockSharesIssued_lbl1" xml:lang="en-US">Common Stock, Shares, Issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesIssued" xlink:to="us-gaap_CommonStockSharesIssued_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_lbl0" xml:lang="en-US">Deferred Tax Liabilities, Property, Plant and Equipment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:to="us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntityEmergingGrowthCompany_lbl0" xml:lang="en-US">Entity Emerging Growth Company</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityEmergingGrowthCompany" xlink:to="dei_EntityEmergingGrowthCompany_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanInterestCost_lbl0" xml:lang="en-US">Defined Benefit Plan, Interest Cost</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanInterestCost" xlink:to="us-gaap_DefinedBenefitPlanInterestCost_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_lbl0" xml:lang="en-US">Class of Warrant or Right, Exercise Price of Warrants or Rights</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl0" xml:lang="en-US">Weighted Average Number of Shares Outstanding, Diluted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_lbl0" xml:lang="en-US">Increase (Decrease) in Other Noncurrent Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xlink:to="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl0" xml:lang="en-US">Intangible Assets, Net (Excluding Goodwill)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:to="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_lbl0" xml:lang="en-US">Retirement Benefits [Text Block]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PrivatePlacementMember_lbl0" xml:lang="en-US">Private Placement [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrivatePlacementMember" xlink:to="us-gaap_PrivatePlacementMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl0" xml:lang="en-US">Accounts Receivable, after Allowance for Credit Loss, Current</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsReceivableNetCurrent" xlink:to="us-gaap_AccountsReceivableNetCurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AdditionalPaidInCapital_lbl0" xml:lang="en-US">Additional Paid in Capital</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdditionalPaidInCapital" xlink:to="us-gaap_AdditionalPaidInCapital_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfRevenueByMajorCustomersByReportingSegmentsTableTextBlock_lbl0" xml:lang="en-US">Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfRevenueByMajorCustomersByReportingSegmentsTableTextBlock" xlink:to="us-gaap_ScheduleOfRevenueByMajorCustomersByReportingSegmentsTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_OriginalMember_lbl0" xml:lang="en-US">Original Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_OriginalMember" xlink:to="onco_OriginalMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_StockIssuedDuringPeriodValueOfssuanceOfCommonStockAndWarrants_lbl1" xml:lang="en-US">Stock Issued During Period Value Ofssuance Of Common Stock And Warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueOfssuanceOfCommonStockAndWarrants" xlink:to="onco_StockIssuedDuringPeriodValueOfssuanceOfCommonStockAndWarrants_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_SeriesBConvertibleRedeemablePreferredStockMember_lbl0" xml:lang="en-US">Series BConvertible Redeemable Preferred Stock Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SeriesBConvertibleRedeemablePreferredStockMember" xlink:to="onco_SeriesBConvertibleRedeemablePreferredStockMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_InitialPublicOfferingShares_lbl1" xml:lang="en-US">Initial Public Offering Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_InitialPublicOfferingShares" xlink:to="onco_InitialPublicOfferingShares_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PaymentsToAcquireProductiveAssets_lbl0" xml:lang="en-US">Payments to Acquire Productive Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquireProductiveAssets" xlink:to="us-gaap_PaymentsToAcquireProductiveAssets_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryValuationReserves_lbl0" xml:lang="en-US">Inventory Valuation Reserves</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryValuationReserves" xlink:to="us-gaap_InventoryValuationReserves_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_Cash_lbl0" xml:lang="en-US">Cash</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Cash" xlink:to="us-gaap_Cash_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl0" xml:lang="en-US">Operating Lease, Right-of-Use Asset</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseRightOfUseAsset" xlink:to="us-gaap_OperatingLeaseRightOfUseAsset_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockDividendsIncomeStatementImpact_lbl0" xml:lang="en-US">Preferred Stock Dividends, Income Statement Impact</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockDividendsIncomeStatementImpact" xlink:to="us-gaap_PreferredStockDividendsIncomeStatementImpact_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharesOutstanding_lbl1" xml:lang="en-US">Shares, Outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharesOutstanding" xlink:to="us-gaap_SharesOutstanding_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccruedLiabilitiesCurrent_lbl1" xml:lang="en-US">Accrued Liabilities, Current</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_lbl0" xml:lang="en-US">Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfAccumulatedOtherComprehensiveIncomeLossTableTextBlock_lbl0" xml:lang="en-US">Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_TemporaryEquitySharesIssued_lbl0" xml:lang="en-US">Temporary Equity, Shares Issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquitySharesIssued" xlink:to="us-gaap_TemporaryEquitySharesIssued_lbl0"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PaymentsToAcquireIntangibleAssets_lbl0" xml:lang="en-US">Payments to Acquire Intangible Assets</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AccruedDeferredOfferingCosts_lbl1" xml:lang="en-US">Accrued Deferred Offering Costs</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetAcquisitionPriceOfAcquisitionExpected_lbl0" xml:lang="en-US">Asset Acquisition, Price of Acquisition, Expected</label>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent" xlink:to="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_lbl0"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseStateRateAdjustment" xlink:to="onco_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseStateRateAdjustment_lbl1"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CumulativeDividends_lbl0" xml:lang="en-US">Cumulative Dividends</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromRepaymentsOfRelatedPartyDebt_lbl0" xml:lang="en-US">Proceeds from (Repayments of) Related Party Debt</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_RestrictedStockForfeitures_lbl1" xml:lang="en-US">Restricted Stock Forfeitures</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_TreasuryStockPolicyPolicyTextBlock_lbl1" xml:lang="en-US">Treasury Stock Policy Policy Text Block</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_TreasuryStockPolicyPolicyTextBlock" xlink:to="onco_TreasuryStockPolicyPolicyTextBlock_lbl1"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_AssetsAbstract_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl0" xml:lang="en-US">Operating Lease, Liability, Noncurrent</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfGoodwillTextBlock_lbl0" xml:lang="en-US">Schedule of Goodwill [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfGoodwillTextBlock" xlink:to="us-gaap_ScheduleOfGoodwillTextBlock_lbl0"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntitySmallBusiness_lbl0" xml:lang="en-US">Entity Small Business</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockDividendsShares_lbl0" xml:lang="en-US">Preferred Stock Dividends, Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockDividendsShares" xlink:to="us-gaap_PreferredStockDividendsShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_CostBasisAbstract_lbl0" xml:lang="en-US">Cost Basis Abstract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CostBasisAbstract" xlink:to="onco_CostBasisAbstract_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharesIssuedPricePerShare_lbl0" xml:lang="en-US">Shares Issued, Price Per Share</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharesIssuedPricePerShare" xlink:to="us-gaap_SharesIssuedPricePerShare_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl0" xml:lang="en-US">Finite-Lived Intangible Asset, Expected Amortization, Year Two</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxLiabilitiesOther_lbl0" xml:lang="en-US">Deferred Tax Liabilities, Other</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxLiabilitiesOther" xlink:to="us-gaap_DeferredTaxLiabilitiesOther_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl1" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl1"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl0" xml:lang="en-US">Temporary Equity, Carrying Amount, Attributable to Parent</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:to="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl0" xml:lang="en-US">Weighted Average Number of Shares Outstanding, Basic</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockConvertibleSharesIssuable_lbl0" xml:lang="en-US">Preferred Stock, Convertible, Shares Issuable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockConvertibleSharesIssuable" xlink:to="us-gaap_PreferredStockConvertibleSharesIssuable_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ContingentWarrantLiabilityShares_lbl1" xml:lang="en-US">Contingent Warrant Liability Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ContingentWarrantLiabilityShares" xlink:to="onco_ContingentWarrantLiabilityShares_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested in Period, Fair Value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RelatedPartyMember_lbl1" xml:lang="en-US">Related Party [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyMember" xlink:to="us-gaap_RelatedPartyMember_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DerivativeLiabilityMeasurementInput_lbl2" xml:lang="en-US">Derivative Liability, Measurement Input</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt_lbl1" xml:lang="en-US">Gain (Loss) on Extinguishment of Debt</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_MeasurementInputExercisePriceMember_lbl0" xml:lang="en-US">Measurement Input, Exercise Price [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputExercisePriceMember" xlink:to="us-gaap_MeasurementInputExercisePriceMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock_lbl0" xml:lang="en-US">Equity [Text Block]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncreaseDecreaseInAccruedLiabilities_lbl0" xml:lang="en-US">Increase (Decrease) in Accrued Liabilities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:to="us-gaap_IncreaseDecreaseInAccruedLiabilities_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PaymentsToAcquireRestrictedCertificatesOfDeposit_lbl0" xml:lang="en-US">Payments to Acquire Restricted Certificates of Deposit</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtConversionOriginalDebtAmount1_lbl0" xml:lang="en-US">Debt Conversion, Original Debt, Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtConversionOriginalDebtAmount1" xlink:to="us-gaap_DebtConversionOriginalDebtAmount1_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="country_US_lbl0" xml:lang="en-US">UNITED STATES</label>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsGross" xlink:to="us-gaap_DeferredTaxAssetsGross_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable_lbl0" xml:lang="en-US">Increase (Decrease) in Accounts Payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInAccountsPayable" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayable_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedExpenses_lbl1" xml:lang="en-US">Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Liabilities Accrued Expenses</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_lbl0" xml:lang="en-US">Net Cash Provided by (Used in) Investing Activities</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockSharesIssued_lbl2" xml:lang="en-US">Preferred Stock, Shares Issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesIssued" xlink:to="us-gaap_PreferredStockSharesIssued_lbl2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ChiefBusinessOfficerMember_lbl0" xml:lang="en-US">Chief Business Officer Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ChiefBusinessOfficerMember" xlink:to="onco_ChiefBusinessOfficerMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_GrossPayPercentage_lbl1" xml:lang="en-US">Gross Pay Percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_GrossPayPercentage" xlink:to="onco_GrossPayPercentage_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl0" xml:lang="en-US">Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_CBOMember_lbl0" xml:lang="en-US">CBOMember</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CBOMember" xlink:to="onco_CBOMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PublicOfPerShare_lbl1" xml:lang="en-US">Public Of Per Share</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PublicOfPerShare" xlink:to="onco_PublicOfPerShare_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_DeferredOfferingCostsPreviouslyPrepaid_lbl1" xml:lang="en-US">Deferred Offering Costs Previously Prepaid</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DeferredOfferingCostsPreviouslyPrepaid" xlink:to="onco_DeferredOfferingCostsPreviouslyPrepaid_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NoncurrentAssets_lbl0" xml:lang="en-US">Long-Lived Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NoncurrentAssets" xlink:to="us-gaap_NoncurrentAssets_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PrepaidExpenseNoncurrent_lbl0" xml:lang="en-US">Prepaid Expense, Noncurrent</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrepaidExpenseNoncurrent" xlink:to="us-gaap_PrepaidExpenseNoncurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationTaxSettlementsStateAndLocal_lbl0" xml:lang="en-US">Effective Income Tax Rate Reconciliation, Tax Settlement, State and Local, Percent</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EffectiveIncomeTaxRateReconciliationTaxSettlementsStateAndLocal" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationTaxSettlementsStateAndLocal_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_CEOMember_lbl0" xml:lang="en-US">CEOMember</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CEOMember" xlink:to="onco_CEOMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_DebtInstrumentDueTerm_lbl1" xml:lang="en-US">Debt Instrument Due Term</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_DebtInstrumentDueTerm" xlink:to="onco_DebtInstrumentDueTerm_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_MaximumMember_lbl0" xml:lang="en-US">Maximum [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MaximumMember" xlink:to="srt_MaximumMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_BusinessTransactionYeare_lbl1" xml:lang="en-US">Business Transaction Yeare</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BusinessTransactionYeare" xlink:to="onco_BusinessTransactionYeare_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_WarrantInducementMember_lbl0" xml:lang="en-US">Warrant Inducement Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WarrantInducementMember" xlink:to="onco_WarrantInducementMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromLicenseFeesReceived_lbl0" xml:lang="en-US">Proceeds from License Fees Received</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromLicenseFeesReceived" xlink:to="us-gaap_ProceedsFromLicenseFeesReceived_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GoodwillImpairmentLoss_lbl0" xml:lang="en-US">Goodwill, Impairment Loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillImpairmentLoss" xlink:to="us-gaap_GoodwillImpairmentLoss_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RelatedPartyTransactionAmountsOfTransaction_lbl0" xml:lang="en-US">Related Party Transaction, Amounts of Transaction</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionAmountsOfTransaction" xlink:to="us-gaap_RelatedPartyTransactionAmountsOfTransaction_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl1" xml:lang="en-US">Common Stock, Par or Stated Value Per Share</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockParOrStatedValuePerShare" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare_lbl1"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfUnvestedRestrictedStockAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfUnvestedRestrictedStockAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfUnvestedRestrictedStockAbstract_lbl" xml:lang="en-US">Schedule Of Unvested Restricted Stock Abstract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfUnvestedRestrictedStockAbstract" xlink:to="onco_ScheduleOfUnvestedRestrictedStockAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_SubscriptionAgreementPMXInvestorPercentage_lbl1" xml:lang="en-US">Subscription Agreement PMXInvestor Percentage</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SubscriptionAgreementPMXInvestorPercentage" xlink:to="onco_SubscriptionAgreementPMXInvestorPercentage_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_Depreciation_lbl0" xml:lang="en-US">Depreciation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Depreciation" xlink:to="us-gaap_Depreciation_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AggregateAgreementAmountInitialAgreement_lbl1" xml:lang="en-US">Aggregate Agreement Amount Initial Agreement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AggregateAgreementAmountInitialAgreement" xlink:to="onco_AggregateAgreementAmountInitialAgreement_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_lbl0" xml:lang="en-US">Class of Warrant or Right, Number of Securities Called by Warrants or Rights</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:to="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl1" xml:lang="en-US">Prepaid Expense and Other Assets, Current</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:to="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_InventoryFinishedGoods_lbl0" xml:lang="en-US">Inventory, Finished Goods, Gross</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InventoryFinishedGoods" xlink:to="us-gaap_InventoryFinishedGoods_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_lbl0" xml:lang="en-US">Defined Benefit Plan, Expected Return (Loss) on Plan Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:to="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ContingentWarrantLiabilityMember_lbl0" xml:lang="en-US">Contingent Warrant Liability Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ContingentWarrantLiabilityMember" xlink:to="onco_ContingentWarrantLiabilityMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited_lbl0" xml:lang="en-US">Stock Issued During Period, Shares, Restricted Stock Award, Forfeited</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited" xlink:to="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfFairValueOfOptionsGrantedAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfFairValueOfOptionsGrantedAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfFairValueOfOptionsGrantedAbstract_lbl" xml:lang="en-US">Schedule Of Fair Value Of Options Granted Abstract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfFairValueOfOptionsGrantedAbstract" xlink:to="onco_ScheduleOfFairValueOfOptionsGrantedAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation_lbl1" xml:lang="en-US">Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation" xlink:to="us-gaap_DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_lbl1" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_lbl1" xml:lang="en-US">Stock Issued During Period, Shares, Restricted Stock Award, Gross</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross" xlink:to="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl0" xml:lang="en-US">Property, Plant and Equipment, Net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentNet" xlink:to="us-gaap_PropertyPlantAndEquipmentNet_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueInputsLevel2Member_lbl0" xml:lang="en-US">Fair Value, Inputs, Level 2 [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueInputsLevel2Member" xlink:to="us-gaap_FairValueInputsLevel2Member_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfBenefitObligationAndTheNetPeriodicBenefitCostAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfBenefitObligationAndTheNetPeriodicBenefitCostAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfBenefitObligationAndTheNetPeriodicBenefitCostAbstract_lbl" xml:lang="en-US">Schedule Of Benefit Obligation And The Net Periodic Benefit Cost Abstract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfBenefitObligationAndTheNetPeriodicBenefitCostAbstract" xlink:to="onco_ScheduleOfBenefitObligationAndTheNetPeriodicBenefitCostAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanContributionsByEmployer_lbl0" xml:lang="en-US">Defined Benefit Plan, Plan Assets, Contributions by Employer</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:to="us-gaap_DefinedBenefitPlanContributionsByEmployer_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_BankruptcyCourtMember_lbl0" xml:lang="en-US">Bankruptcy Court Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_BankruptcyCourtMember" xlink:to="onco_BankruptcyCourtMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Asset Acquired and Liability Assumed, Lease Obligation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPeriodIncreaseDecrease_lbl0" xml:lang="en-US">Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Period Increase (Decrease)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPeriodIncreaseDecrease" xlink:to="us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPeriodIncreaseDecrease_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_InitialPaymentAmount_lbl1" xml:lang="en-US">Initial Payment Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_InitialPaymentAmount" xlink:to="onco_InitialPaymentAmount_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ClassOfWarrantOrRightUnissued_lbl0" xml:lang="en-US">Class of Warrant or Right, Unissued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightUnissued" xlink:to="us-gaap_ClassOfWarrantOrRightUnissued_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtDisclosureTextBlock_lbl0" xml:lang="en-US">Debt Disclosure [Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtDisclosureTextBlock" xlink:to="us-gaap_DebtDisclosureTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PrepaidInsurance_lbl0" xml:lang="en-US">Prepaid Insurance</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueAdjustmentOfWarrants_lbl1" xml:lang="en-US">Fair Value Adjustment of Warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueAdjustmentOfWarrants" xlink:to="us-gaap_FairValueAdjustmentOfWarrants_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_FiniteLivedIntangibleAssetCost_lbl1" xml:lang="en-US">Finite Lived Intangible Asset Cost</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_CommercialSaleTerm_lbl1" xml:lang="en-US">Commercial Sale Term</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_UnlabeledAbstract_lbl0" xml:lang="en-US">Unlabeled Abstract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UnlabeledAbstract" xlink:to="onco_UnlabeledAbstract_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_IncomeTaxReconciliationNondeductibleExpenseOfficersCompensation_lbl1" xml:lang="en-US">Income Tax Reconciliation Nondeductible Expense Officers Compensation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IncomeTaxReconciliationNondeductibleExpenseOfficersCompensation" xlink:to="onco_IncomeTaxReconciliationNondeductibleExpenseOfficersCompensation_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueGranted_lbl1" xml:lang="en-US">Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value Granted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueGranted" xlink:to="onco_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValueGranted_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PayableAverageDiscountRatePercentage_lbl1" xml:lang="en-US">Payable Average Discount Rate Percentage</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockConvertibleConversionPrice_lbl0" xml:lang="en-US">Preferred Stock, Convertible, Conversion Price</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockConvertibleConversionPrice" xlink:to="us-gaap_PreferredStockConvertibleConversionPrice_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_StockIssuedDuringPeriodValueOfChangesInPensionBenefitObligation_lbl1" xml:lang="en-US">Stock Issued During Period Value Of Changes In Pension Benefit Obligation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueOfChangesInPensionBenefitObligation" xlink:to="onco_StockIssuedDuringPeriodValueOfChangesInPensionBenefitObligation_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssuedDuringPeriodSharesOther_lbl0" xml:lang="en-US">Stock Issued During Period, Shares, Other</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesOther" xlink:to="us-gaap_StockIssuedDuringPeriodSharesOther_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Exercise Price</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_lbl0"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RelatedPartyTransactionsAbstract_lbl" xml:lang="en-US">Related Party Transactions [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionsAbstract" xlink:to="us-gaap_RelatedPartyTransactionsAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_GrantDateFairValueOfStockOption_lbl1" xml:lang="en-US">Grant Date Fair Value Of Stock Option</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_GrantDateFairValueOfStockOption" xlink:to="onco_GrantDateFairValueOfStockOption_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_IncomeTaxReconciliationNondeductibleExpenseDerivativeLiability_lbl1" xml:lang="en-US">Income Tax Reconciliation Nondeductible Expense Derivative Liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IncomeTaxReconciliationNondeductibleExpenseDerivativeLiability" xlink:to="onco_IncomeTaxReconciliationNondeductibleExpenseDerivativeLiability_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_ScheduleOfCondensedFinancialStatementsTableTextBlock_lbl0" xml:lang="en-US">Condensed Financial Statements [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ScheduleOfCondensedFinancialStatementsTableTextBlock" xlink:to="srt_ScheduleOfCondensedFinancialStatementsTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_lbl0" xml:lang="en-US">Finite-Lived Intangible Assets, Gross</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsGross" xlink:to="us-gaap_FiniteLivedIntangibleAssetsGross_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RelatedPartyTransactionsDisclosureTextBlock_lbl0" xml:lang="en-US">Related Party Transactions Disclosure [Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionsDisclosureTextBlock" xlink:to="us-gaap_RelatedPartyTransactionsDisclosureTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_InventoryFairValue_lbl1" xml:lang="en-US">Inventory Fair Value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_InventoryFairValue" xlink:to="onco_InventoryFairValue_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable_lbl0" xml:lang="en-US">Asset Acquisition, Consideration Transferred, Equity Interest Issued and Issuable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable" xlink:to="us-gaap_AssetAcquisitionConsiderationTransferredEquityInterestIssuedAndIssuable_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_lbl2" xml:lang="en-US">Equity, Including Portion Attributable to Noncontrolling Interest</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_lbl2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_MinorityInterest_lbl0" xml:lang="en-US">Equity, Attributable to Noncontrolling Interest</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_RoyaltyExpense_lbl0" xml:lang="en-US">Royalty Expense</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_lbl0" xml:lang="en-US">Share-Based Payment Arrangement, Option, Activity [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:to="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_lbl0" xml:lang="en-US">Property, Plant and Equipment, Policy [Policy Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:to="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CommercialAndIndustrialSectorMember_lbl0" xml:lang="en-US">Commercial and Industrial Sector [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommercialAndIndustrialSectorMember" xlink:to="us-gaap_CommercialAndIndustrialSectorMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_lbl0" xml:lang="en-US">Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:to="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AssetAcquisitionConsiderationTransferredENTADFIIntangible_lbl1" xml:lang="en-US">Asset Acquisition Consideration Transferred ENTADFIIntangible</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AssetAcquisitionConsiderationTransferredENTADFIIntangible" xlink:to="onco_AssetAcquisitionConsiderationTransferredENTADFIIntangible_lbl1"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_lbl0" xml:lang="en-US">Sale of Stock, Number of Shares Issued in Transaction</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction" xlink:to="us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_lbl0" xml:lang="en-US">Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate" xlink:to="us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_lbl0"/>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditExcludingServiceCostStatementOfIncomeOrComprehensiveIncomeExtensibleList" xlink:to="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostCreditExcludingServiceCostStatementOfIncomeOrComprehensiveIncomeExtensibleList_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_SalesPaymentsAmount_lbl1" xml:lang="en-US">Sales Payments Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_SalesPaymentsAmount" xlink:to="onco_SalesPaymentsAmount_lbl1"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementOfFinancialPositionAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementOfFinancialPositionAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StatementOfFinancialPositionAbstract_lbl" xml:lang="en-US">Statement of Financial Position [Abstract]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl0" xml:lang="en-US">Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueMeasurementPolicyPolicyTextBlock_lbl0" xml:lang="en-US">Fair Value Measurement, Policy [Policy Text Block]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_SignificantAgreementsTextBlock_lbl1" xml:lang="en-US">Significant Agreements Text Block</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherCostOfOperatingRevenue_lbl0" xml:lang="en-US">Other Cost of Operating Revenue</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock_lbl0" xml:lang="en-US">Proceeds from Issuance of Convertible Preferred Stock</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_lbl0" xml:lang="en-US">Deferred State and Local Income Tax Expense (Benefit)</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccountsReceivableNet_lbl0" xml:lang="en-US">Accounts Receivable, after Allowance for Credit Loss</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntityFilerCategory_lbl0" xml:lang="en-US">Entity Filer Category</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_lbl0" xml:lang="en-US">Defined Benefit Plan, Net Periodic Benefit Cost (Credit)</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock_lbl0" xml:lang="en-US">Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock" xlink:to="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges_lbl0" xml:lang="en-US">Gain (Loss) on Sale of Assets and Asset Impairment Charges</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromSaleOfOtherInvestments_lbl0" xml:lang="en-US">Proceeds from Sale of Other Investments</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_Assets_lbl1" xml:lang="en-US">Assets</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_TreasuryStockValue_lbl0" xml:lang="en-US">Treasury Stock, Value</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromWarrantExercises_lbl0" xml:lang="en-US">Proceeds from Warrant Exercises</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_lbl0" xml:lang="en-US">Business Acquisition, Pro Forma Net Income (Loss)</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterest_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterest" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedLessNoncontrollingInterest_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccruedProfessionalFeesCurrentAndNoncurrent_lbl0" xml:lang="en-US">Accrued Professional Fees</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccruedProfessionalFeesCurrentAndNoncurrent" xlink:to="us-gaap_AccruedProfessionalFeesCurrentAndNoncurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_January2024Member_lbl0" xml:lang="en-US">January2024 Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PaymentsForPurchaseOfTreasuryShares_lbl1" xml:lang="en-US">Payments For Purchase Of Treasury Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PaymentsForPurchaseOfTreasuryShares" xlink:to="onco_PaymentsForPurchaseOfTreasuryShares_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PercentageOfSubscription_lbl1" xml:lang="en-US">Percentage Of Subscription</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_PercentageOfSubscription" xlink:to="onco_PercentageOfSubscription_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_VotingInterestPercentage_lbl1" xml:lang="en-US">Voting Interest Percentage</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl1" xml:lang="en-US">Income Tax Expense (Benefit)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxExpenseBenefit_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherAccruedLiabilitiesCurrentAndNoncurrent_lbl0" xml:lang="en-US">Other Accrued Liabilities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherAccruedLiabilitiesCurrentAndNoncurrent" xlink:to="us-gaap_OtherAccruedLiabilitiesCurrentAndNoncurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DerivativeLiabilitiesCurrent_lbl0" xml:lang="en-US">Derivative Liability, Current</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeLiabilitiesCurrent" xlink:to="us-gaap_DerivativeLiabilitiesCurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock_lbl0" xml:lang="en-US">Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock" xlink:to="us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_August2022PrivatePlacementMember_lbl0" xml:lang="en-US">August2022 Private Placement Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl0" xml:lang="en-US">Deferred Income Tax Expense (Benefit)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_lbl0" xml:lang="en-US">Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xlink:to="us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_lbl0" xml:lang="en-US">Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures" xlink:to="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ParentMember_lbl0" xml:lang="en-US">Parent [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ParentMember" xlink:to="us-gaap_ParentMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_WeightedAverageDiscountRateThereafter_lbl1" xml:lang="en-US">Weighted Average Discount Rate Thereafter</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WeightedAverageDiscountRateThereafter" xlink:to="onco_WeightedAverageDiscountRateThereafter_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense_lbl0" xml:lang="en-US">Employee Stock Ownership Plan (ESOP), Compensation Expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense" xlink:to="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_CashPaymentToTheSeller_lbl1" xml:lang="en-US">Cash Payment To The Seller</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_CashPaymentToTheSeller" xlink:to="onco_CashPaymentToTheSeller_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_PrefundedWarrantsExercised_lbl1" xml:lang="en-US">Prefunded Warrants Exercised</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetAcquisitionConsiderationTransferred_lbl1" xml:lang="en-US">Asset Acquisition, Consideration Transferred</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingIncomeLossMember_lbl1" xml:lang="en-US">Operating Income (Loss) [Member]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetAcquisitionConsiderationTransferredOtherAssets_lbl0" xml:lang="en-US">Asset Acquisition, Consideration Transferred, Other Assets</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AssetPurchaseAgreementMember_lbl0" xml:lang="en-US">Asset Purchase Agreement Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_NettingProceeds_lbl1" xml:lang="en-US">Netting Proceeds</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_UTHealthAgreementMember_lbl0" xml:lang="en-US">UTHealth Agreement Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="country_CH_lbl1" xml:lang="en-US">SWITZERLAND</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueInputsLevel1Member_lbl0" xml:lang="en-US">Fair Value, Inputs, Level 1 [Member]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_StJudeChildrensHospitalMember_lbl0" xml:lang="en-US">St Jude Childrens Hospital Member</label>
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    <loc xlink:type="locator" xlink:label="onco_ScheduleOfLongLivedByGeographicalAreaAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfLongLivedByGeographicalAreaAbstract"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_lbl0" xml:lang="en-US">Defined Benefit Plan, Benefit Obligation, Benefits Paid</label>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestrictedStockMember" xlink:to="us-gaap_RestrictedStockMember_lbl1"/>
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    <loc xlink:type="locator" xlink:label="onco_ScheduleOfFairValueOfFinancialInstrumentsMeasuredOnARecurringBasisAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfFairValueOfFinancialInstrumentsMeasuredOnARecurringBasisAbstract"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities_lbl0" xml:lang="en-US">Net Cash Provided by (Used in) Operating Activities</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_TwoThousandTwentyTwoPlanMember_lbl1" xml:lang="en-US">Two Thousand Twenty Two Plan Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_IssuanceOfCommonStockAndWarrantsInPrivatePlacementNet_lbl1" xml:lang="en-US">Issuance Of Common Stock And Warrants In Private Placement Net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_IssuanceOfCommonStockAndWarrantsInPrivatePlacementNet" xlink:to="onco_IssuanceOfCommonStockAndWarrantsInPrivatePlacementNet_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SaleOfStockPricePerShare_lbl0" xml:lang="en-US">Sale of Stock, Price Per Share</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleOfStockPricePerShare" xlink:to="us-gaap_SaleOfStockPricePerShare_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_OtherComprehensiveIncomeLossForeignCurrencyTranslationsAdjustmentTax_lbl1" xml:lang="en-US">Other Comprehensive Income Loss Foreign Currency Translations Adjustment Tax</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_OtherComprehensiveIncomeLossForeignCurrencyTranslationsAdjustmentTax" xlink:to="onco_OtherComprehensiveIncomeLossForeignCurrencyTranslationsAdjustmentTax_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl1" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_MinorityInterestOwnershipPercentageByParent_lbl0" xml:lang="en-US">Subsidiary, Ownership Percentage, Parent</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_AmendmentFlag_lbl0" xml:lang="en-US">Amendment Flag</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl1" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OperatingIncomeLoss_lbl0" xml:lang="en-US">Operating Income (Loss)</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock_lbl0" xml:lang="en-US">Foreign Currency Transactions and Translations Policy [Policy Text Block]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="dei_EntityCentralIndexKey_lbl0" xml:lang="en-US">Entity Central Index Key</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_TreasuryStockCommonShares_lbl0" xml:lang="en-US">Treasury Stock, Common, Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TreasuryStockCommonShares" xlink:to="us-gaap_TreasuryStockCommonShares_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_StockIssuedDuringPeriodValueIssuanceOfSeriesAPreferredStock_lbl1" xml:lang="en-US">Stock Issued During Period Value Issuance Of Series APreferred Stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockIssuedDuringPeriodValueIssuanceOfSeriesAPreferredStock" xlink:to="onco_StockIssuedDuringPeriodValueIssuanceOfSeriesAPreferredStock_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AugustContingentWarrantsMember_lbl0" xml:lang="en-US">August Contingent Warrants Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_AugustContingentWarrantsMember" xlink:to="onco_AugustContingentWarrantsMember_lbl0"/>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ConvertiblePreferredStockSharesReservedForFutureIssuance_lbl0" xml:lang="en-US">Convertible Preferred Stock, Shares Reserved for Future Issuance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConvertiblePreferredStockSharesReservedForFutureIssuance" xlink:to="us-gaap_ConvertiblePreferredStockSharesReservedForFutureIssuance_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockConvertibleConversionPriceDecrease_lbl0" xml:lang="en-US">Preferred Stock, Convertible, Conversion Price, Decrease</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockConvertibleConversionPriceDecrease" xlink:to="us-gaap_PreferredStockConvertibleConversionPriceDecrease_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock_lbl0" xml:lang="en-US">Schedule of Net Periodic Benefit Cost Not yet Recognized [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock" xlink:to="us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_MeasurementInputOptionVolatilityMember_lbl0" xml:lang="en-US">Measurement Input, Option Volatility [Member]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_StockIssuedDuringPeriodSharesIssuanceOfCommonStockAndSeriesBPreferredStockInConnectionWithPMXTransaction_lbl2" xml:lang="en-US">Stock Issued During Period Shares Issuance Of Common Stock And Series BPreferred Stock In Connection With PMXTransaction</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTextBlock_lbl0" xml:lang="en-US">Schedule of Defined Benefit Plans Disclosures [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTextBlock" xlink:to="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LegalFees_lbl1" xml:lang="en-US">Legal Fees</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock_lbl0" xml:lang="en-US">Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IntangibleAssetsFiniteLivedPolicy_lbl0" xml:lang="en-US">Intangible Assets, Finite-Lived, Policy [Policy Text Block]</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromIssuanceInitialPublicOffering_lbl1" xml:lang="en-US">Proceeds from Issuance Initial Public Offering</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_DevelopmentMilestonesMember_lbl0" xml:lang="en-US">Development Milestones Member</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_lbl1" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CostMaintenance_lbl0" xml:lang="en-US">Cost, Maintenance</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_SharePrice_lbl0" xml:lang="en-US">Share Price</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_IncreaseInTheFairValueOfThePreferredInvestmentOptions_lbl1" xml:lang="en-US">Increase In The Fair Value Of The Preferred Investment Options</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_lbl0" xml:lang="en-US">Stock Issued During Period, Value, Conversion of Convertible Securities</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AssetsCurrentAbstract_lbl0" xml:lang="en-US">Assets, Current [Abstract]</label>
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    <loc xlink:type="locator" xlink:label="onco_ScheduleOfStockOptionsAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfStockOptionsAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfStockOptionsAbstract_lbl" xml:lang="en-US">Schedule Of Stock Options Abstract</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_MarketOfferingAgreementMember_lbl0" xml:lang="en-US">Market Offering Agreement Member</label>
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_EarningsPerSharePolicyTextBlock_lbl0" xml:lang="en-US">Earnings Per Share, Policy [Policy Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EarningsPerSharePolicyTextBlock" xlink:to="us-gaap_EarningsPerSharePolicyTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredFederalIncomeTaxExpenseBenefit_lbl0" xml:lang="en-US">Deferred Federal Income Tax Expense (Benefit)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredFederalIncomeTaxExpenseBenefit_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_StockOptionsMember_lbl0" xml:lang="en-US">Stock Options Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_StockOptionsMember" xlink:to="onco_StockOptionsMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_lbl0" xml:lang="en-US">Defined Benefit Plan, Expected Future Benefit Payment, Year Four</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_MeasurementInputRiskFreeInterestRateMember_lbl2" xml:lang="en-US">Measurement Input, Risk Free Interest Rate [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MeasurementInputRiskFreeInterestRateMember" xlink:to="us-gaap_MeasurementInputRiskFreeInterestRateMember_lbl2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding_lbl1" xml:lang="en-US">Class of Warrant or Right, Outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightOutstanding" xlink:to="us-gaap_ClassOfWarrantOrRightOutstanding_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_lbl0" xml:lang="en-US">Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures" xlink:to="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromStockOptionsExercised_lbl0" xml:lang="en-US">Proceeds from Stock Options Exercised</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromStockOptionsExercised" xlink:to="us-gaap_ProceedsFromStockOptionsExercised_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_TradeNamesMember_lbl1" xml:lang="en-US">Trade Names [Member]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TradeNamesMember" xlink:to="us-gaap_TradeNamesMember_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PaymentsForFees_lbl1" xml:lang="en-US">Payments for Other Fees</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsForFees" xlink:to="us-gaap_PaymentsForFees_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_OtherGeneralExpense_lbl0" xml:lang="en-US">Other General Expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherGeneralExpense" xlink:to="us-gaap_OtherGeneralExpense_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LongTermDebtMaturityDate_lbl0" xml:lang="en-US">Long-Term Debt, Maturity Date</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebtMaturityDate" xlink:to="us-gaap_LongTermDebtMaturityDate_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_GoodwillForeignCurrencyTranslationGainLoss_lbl0" xml:lang="en-US">Goodwill, Foreign Currency Translation Gain (Loss)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:to="us-gaap_GoodwillForeignCurrencyTranslationGainLoss_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DividendsPaidinkind_lbl0" xml:lang="en-US">Dividends, Paid-in-kind</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendsPaidinkind" xlink:to="us-gaap_DividendsPaidinkind_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_lbl0" xml:lang="en-US">Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtInstrumentFaceAmount_lbl0" xml:lang="en-US">Debt Instrument, Face Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentFaceAmount" xlink:to="us-gaap_DebtInstrumentFaceAmount_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_AccruedUtilitiesCurrentAndNoncurrent_lbl0" xml:lang="en-US">Accrued Utilities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccruedUtilitiesCurrentAndNoncurrent" xlink:to="us-gaap_AccruedUtilitiesCurrentAndNoncurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProfessionalAndContractServicesExpense_lbl0" xml:lang="en-US">Professional and Contract Services Expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProfessionalAndContractServicesExpense" xlink:to="us-gaap_ProfessionalAndContractServicesExpense_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets_lbl0" xml:lang="en-US">Deferred Tax Assets, Goodwill and Intangible Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xlink:to="us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_LiabilitiesCurrent_lbl0" xml:lang="en-US">Liabilities, Current</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_LiabilitiesCurrent_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="srt_ScheduleOfCondensedIncomeStatementTableTextBlock_lbl0" xml:lang="en-US">Condensed Income Statement [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ScheduleOfCondensedIncomeStatementTableTextBlock" xlink:to="srt_ScheduleOfCondensedIncomeStatementTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FederalStateAndLocalIncomeTaxExpenseBenefitContinuingOperations_lbl0" xml:lang="en-US">Federal, State, and Local, Income Tax Expense (Benefit), Continuing Operations</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FederalStateAndLocalIncomeTaxExpenseBenefitContinuingOperations" xlink:to="us-gaap_FederalStateAndLocalIncomeTaxExpenseBenefitContinuingOperations_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_WarrantsIssuedForSettlementOfContingentWarrants_lbl2" xml:lang="en-US">Warrants Issued For Settlement Of Contingent Warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_WarrantsIssuedForSettlementOfContingentWarrants" xlink:to="onco_WarrantsIssuedForSettlementOfContingentWarrants_lbl2"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_TwoThousandTwentyTwoEquityIncentivePlanMember_lbl0" xml:lang="en-US">Two Thousand Twenty Two Equity Incentive Plan Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_TwoThousandTwentyTwoEquityIncentivePlanMember" xlink:to="onco_TwoThousandTwentyTwoEquityIncentivePlanMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_lbl1" xml:lang="en-US">Proceeds from Issuance of Private Placement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceOfPrivatePlacement" xlink:to="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_lbl1"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfEstimatedFairValuesOfAssetsAcquiredAndLiabilitiesAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfEstimatedFairValuesOfAssetsAcquiredAndLiabilitiesAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfEstimatedFairValuesOfAssetsAcquiredAndLiabilitiesAbstract_lbl" xml:lang="en-US">Schedule Of Estimated Fair Values Of Assets Acquired And Liabilities Abstract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfEstimatedFairValuesOfAssetsAcquiredAndLiabilitiesAbstract" xlink:to="onco_ScheduleOfEstimatedFairValuesOfAssetsAcquiredAndLiabilitiesAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_lbl0" xml:lang="en-US">Defined Benefit Plan, Expected Future Benefit Payment, Year Two</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" xlink:to="us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets_lbl0" xml:lang="en-US">Deferred Tax Liabilities, Intangible Assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xlink:to="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueOptionChangesInFairValueGainLoss1_lbl0" xml:lang="en-US">Fair Value, Option, Changes in Fair Value, Gain (Loss)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueOptionChangesInFairValueGainLoss1" xlink:to="us-gaap_FairValueOptionChangesInFairValueGainLoss1_lbl0"/>
    <loc xlink:type="locator" xlink:label="onco_ScheduleOfRevenueByGeographicalAreaAbstract" xlink:href="onco-20231231.xsd#onco_ScheduleOfRevenueByGeographicalAreaAbstract"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_ScheduleOfRevenueByGeographicalAreaAbstract_lbl" xml:lang="en-US">Schedule Of Revenue By Geographical Area Abstract</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_ScheduleOfRevenueByGeographicalAreaAbstract" xlink:to="onco_ScheduleOfRevenueByGeographicalAreaAbstract_lbl"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_lbl0" xml:lang="en-US">Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:to="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CostOfRevenue_lbl0" xml:lang="en-US">Cost of Revenue</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_lbl1" xml:lang="en-US">Stock Issued During Period, Value, Restricted Stock Award, Gross</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross" xlink:to="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_lbl1"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_UniversityOfTexasHealthScienceCenterAtSanAntonioMember_lbl0" xml:lang="en-US">University Of Texas Health Science Center At San Antonio Member</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="onco_UniversityOfTexasHealthScienceCenterAtSanAntonioMember" xlink:to="onco_UniversityOfTexasHealthScienceCenterAtSanAntonioMember_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_lbl0" xml:lang="en-US">Defined Benefit Plan, Plan Assets, Benefits Paid</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid" xlink:to="us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_CashFDICInsuredAmount_lbl0" xml:lang="en-US">Cash, FDIC Insured Amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CashFDICInsuredAmount" xlink:to="us-gaap_CashFDICInsuredAmount_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_lbl0" xml:lang="en-US">Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:to="us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_lbl0" xml:lang="en-US">Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_ScheduleOfInventoryCurrentTableTextBlock_lbl0" xml:lang="en-US">Schedule of Inventory, Current [Table Text Block]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfInventoryCurrentTableTextBlock" xlink:to="us-gaap_ScheduleOfInventoryCurrentTableTextBlock_lbl0"/>
    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_lbl0" xml:lang="en-US">Income (Loss) from Continuing Operations before Income Taxes, Foreign</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="onco_AssetAcquisitionConsiderationTransferredInventory_lbl1" xml:lang="en-US">Asset Acquisition Consideration Transferred Inventory</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_DebtInstrumentMaturityDate_lbl0" xml:lang="en-US">Debt Instrument, Maturity Date</label>
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    <label xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label" xlink:label="us-gaap_PreferredStockValue_lbl0" xml:lang="en-US">Preferred Stock, Value, Issued</label>
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