Derivative instruments Derivatives [member] Financial assets, at fair value Financial assets, at fair value Number of outstanding warrants subject to non-market performance condition (in shares) Number Of Warrants Outstanding Subject To Non-Market Performance Condition Number Of Warrants Outstanding Subject To Non-Market Performance Condition Statistical Measurement [Domain] Statistical Measurement [Domain] Disclosure of geographical areas [line items] Disclosure of geographical areas [line items] Borrowings Non-current portion of other non-current borrowings Employee-related receivables Current Receivables for Employee Benefits Current Receivables for Employee Benefits Principal Agreements [Domain] Principal Agreements [Domain] Principal Agreements [Domain] Acquisitions of property, plant and equipment Purchase of property, plant and equipment, classified as investing activities Sub-contracting, studies and research Sub-Contracting, Studies And Research Expenses Sub-Contracting, Studies And Research Expenses BSA-2015-12 BSA-2015-12 [Member] BSA-2015-12 Assets Acquisitions [Axis] Assets Acquisitions [Axis] Assets Acquisitions Day-one gain on recognition of financial liabilities Gains Arising From Recognition Of Financial Liabilities Gains Arising From Recognition Of Financial Liabilities TRANSLATION RESERVE Reserve of exchange differences on translation [member] Entity File Number Entity File Number Liabilities arising from financing activities [axis] Liabilities arising from financing activities [axis] Impairment loss recognised in profit or loss, other intangible assets Impairment loss recognised in profit or loss, intangible assets other than goodwill Other financial assets Total other non-current financial assets Other non-current financial assets Disclosure of reconciliation of intangible assets Disclosure of detailed information about intangible assets [text block] Repayments of non-convertible bond loans Repayments Of Non-Convertible Loans Notes Repayments Of Non-Convertible Loans Notes Total operating expenses Operating expenses Operating expense Operating expense Trade payables and other current liabilities Trade Payables And Other Current Liabilities [Member] Trade Payables And Other Current Liabilities Appropriation of prior period net loss Increase (decrease) through appropriation of retained earnings, equity Classes of share capital [axis] Classes of share capital [axis] Assets Acquisitions [Domain] Assets Acquisitions [Domain] Assets Acquisitions [Domain] Social taxes related to AGAs Expense From Equity-Settled Share-Based Payment Transactions, Social Taxes Expense From Equity-Settled Share-Based Payment Transactions, Social Taxes Repayment / (disbursement) of the advance made to the Nice CHU Advances Reimbursed By (Made To) Contract Research Organizations Advances Reimbursed By (Made To) Contract Research Organizations Cash and cash equivalents [abstract] Disclosure of reconciliation of liabilities arising from financing activities Disclosure of reconciliation of liabilities arising from financing activities [text block] Increase in operating expenses, development of new indications for obefazimod Increase (Decrease) In Operating Expenses, Development Of New Indications For Obefazimod Increase (Decrease) In Operating Expenses, Development Of New Indications For Obefazimod Total shareholders’ equity Equity at beginning of period Equity at end of period Equity Equity BSA-2018-1 BSA-2018-1 [Member] BSA-2018-1 Kreos/Claret Minimal Return Indemnifications Kreos & Claret Minimum Return Indemnifications [Member] Kreos & Claret Minimum Return Indemnifications BCE-2018-5 BCE-2018-5 [Member] BCE-2018-5 Financial gain (loss) Finance income (cost) AGA-2025-6 AGA-2025-6 [Member] AGA-2025-6 Disclosure of detailed information about borrowings [table] Disclosure of detailed information about borrowings [table] Number of instruments exercised (in shares) Number of instruments exercised (in shares) Number of instruments vested (in shares) Number of other equity instruments exercised or vested in share-based payment arrangement Increase in operating expenses, UC clinical program Increase (Decrease) In Operating Expenses, UC Clinical Program Increase (Decrease) In Operating Expenses, UC Clinical Program Kreos & Claret bond loans Kreos & Claret Bond Loans [Member] Kreos & Claret Bond Loans Clinical Trial Program [Axis] Clinical Trial Program [Axis] Clinical Trial Program Statement of comprehensive income [abstract] Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items] Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items] Disclosure Of Fair Value Measurement Of Assets And Liabilities Statement of changes in equity [line items] Statement of changes in equity [line items] Derivative financial liabilities, undiscounted cash flows Derivative financial liabilities, undiscounted cash flows Increase in operating expenses, CD program Increase (Decrease) In Operating Expenses, CD Program Increase (Decrease) In Operating Expenses, CD Program Other receivables and assets Other assets Reasonably possible change in risk variable, percent Sensitivity Analysis For Types Of Market Risk, Reasonably Possible Change In Risk Variable, Percent Sensitivity Analysis For Types Of Market Risk, Reasonably Possible Change In Risk Variable, Percent Types of contracts [domain] Types of contracts [domain] Corporate information and statement of IFRS compliance [abstract] Subsidies Income from government grants Disclosure of detailed information about property, plant and equipment [line items] Disclosure of detailed information about property, plant and equipment [line items] Net loss for the period Retained earnings, profit (loss) for reporting period Sales and marketing expenses Sales And Marketing Expense [Member] Sales And Marketing Expense Revaluation of cash equivalents measured at fair value Revaluation Of Cash Equivalents Measured At Fair Value Revaluation Of Cash Equivalents Measured At Fair Value Number of instruments lapsed (in shares) Number of other equity instruments expired in share-based payment arrangement Increase (decrease) in carrying value due to reasonably possible increase in unobservable input liabilities Increase (Decrease) In Carrying Value Due To Reasonably Possible Increase In Unobservable Input Liabilities Increase (Decrease) In Carrying Value Due To Reasonably Possible Increase In Unobservable Input Liabilities STRIKE PRICE PER SHARE (in euro per share) Equity Instrument Strike Price, Other Equity Instruments Granted Equity Instrument Strike Price, Other Equity Instruments Granted Disclosure of geographical areas [table] Disclosure of geographical areas [table] Discount rate Discount rate, measurement input [member] Number of ADS per Ordinary Shares Number of ADS per Ordinary Shares Number of ADS per Ordinary Shares ABTECT-2 ABTECT-2 [Member] ABTECT-2 Contribution to Group's liabilities, percentage Contribution To Group's Liabilities, Percentage Contribution To Group's Liabilities, Percentage Conversion price per share (in euro per share) Conversion Price Per Share, Measurement Input [Member] Conversion Price Per Share, Measurement Input Peak penetration Peak Penetration, Measurement Input [Member] Peak Penetration, Measurement Input Derivative instruments Current derivative financial liabilities ASSETS AT FAIR VALUE THROUGH PROFIT AND LOSS Financial assets at fair value through profit or loss, category [member] Depreciation expense, lease Depreciation Expense, Lease Depreciation Expense, Lease Statement of financial position [abstract] BCE-2017-2 BCE-2017-2 [Member] BCE-2017-2 Sales and marketing Sales and marketing expense Cover [Abstract] Borrowings Borrowings [Member] Borrowings Maximum Maximum [Member] Net proceeds from sale of royalty certificates Proceeds From Conditional Advances Proceeds From Conditional Advances Exercise price per share (in euro per share) Exercise Price Per Share, Measurement Input [Member] Exercise Price Per Share, Measurement Input Other Other adjustments for non-cash items Lease facilities Lease Facilities [Member] Lease Facilities Total current liabilities Current liabilities Employees [Abstract] Employees [Abstract] Classes of intangible assets other than goodwill [axis] Classes of intangible assets other than goodwill [axis] Receivable from Citibank Current Receivables From Citibank Current Receivables From Citibank AGA-2025-1 AGA-2025-1 [Member] AGA-2025-1 Kreos & Claret convertible notes (OCABSA) Kreos/Claret BSA Kreos & Claret Financing, Tranche A [Member] Kreos & Claret Financing, Tranche A Trade and other receivables [abstract] AGA-2024 AGA-2024 [Member] AGA-2024 Expenses by nature [abstract] BSA-2025-3 BSA-2025-3 [Member] BSA-2025-3 Decrease in deposits Proceeds From Reimbursements Of Deposits Proceeds From Reimbursements Of Deposits Premiums related to share capital Share premium Cash flows provided by (used in) financing activities Cash flows from (used in) financing activities [abstract] Social security and other Current payables on social security and taxes other than income tax Classes of liabilities [domain] Classes of liabilities [domain] Cash and cash equivalents Cash And Cash Equivalents [Member] Cash And Cash Equivalents Expense on lease liabilities Expense On Lease Liabilities Expense On Lease Liabilities Disclosure of quantitative information about right-of-use assets [line items] Disclosure of quantitative information about right-of-use assets [line items] Operating expenses Disclosure of other operating expense [text block] Disclosure Of Financial Gain (Loss) [Line Items] Disclosure Of Financial Gain (Loss) [Line Items] Disclosure Of Financial Gain (Loss) [Line Items] Total comprehensive income (loss) for the period Comprehensive income PGE Prêt Garanti Par l'Etat (PGE) [Member] Prêt Garanti Par l'Etat (PGE) Sale Of Stock [Domain] Sale Of Stock [Domain] Sale Of Stock [Domain] Statement of changes in equity [abstract] Measurement [domain] Measurement [domain] Research tax credit ("CIR") Income From Research Tax Credit Income From Research Tax Credit Interest paid Decrease Through Interest Paid, Liabilities Arising From Financing Activities Decrease Through Interest Paid, Liabilities Arising From Financing Activities Convertible loans notes Convertible Loans Notes Convertible Loans Notes Basis of preparation Disclosure of basis of preparation of financial statements [text block] AGA-2023-5 AGA-2023-5 [Member] AGA-2023-5 Disclosure Of Employee Workforce [Line Items] Disclosure Of Employee Workforce [Line Items] Disclosure Of Employee Workforce [Line Items] Royalty certificate, maximum amount Royalty Certificate, Maximum Amount Royalty Certificate, Maximum Amount AGA-2024-5 AGA-2024-5 [Member] AGA-2024-5 BCEs Total BCEs Founders’ Share Subscription Warrants (BCE) [Member] Founders’ Share Subscription Warrants (BCE) Placebo-adjusted clinical remission rate Placebo-Adjusted Clinical Remission Rate Placebo-Adjusted Clinical Remission Rate Deposits Short-term deposits, not classified as cash equivalents Research and development expenses Research And Development Expenses [Member] Research And Development Expenses Disclosure of detailed information about financial instruments [line items] Disclosure of detailed information about financial instruments [line items] Document Fiscal Period Focus Document Fiscal Period Focus Gross proceeds from non-convertible loans notes Gross Proceeds From Non-Convertible Loans Notes Gross Proceeds From Non-Convertible Loans Notes Significant unobservable input, assets Significant unobservable input, assets BUILDINGS Buildings Buildings [member] TOTAL ASSETS Financial assets Assets Assets Number of instruments issued (in shares) NUMBER OF BSAs (in shares) Number of other equity instruments granted in share-based payment arrangement Types of risks [domain] Types of risks [domain] Forgiveness of conditional advances Adjustments For Forgiveness Of Covid 19 Conditional Advances Adjustments For Forgiveness Of Covid 19 Conditional Advances Decrease / (increase) in other receivables and related accounts Adjustments for decrease (increase) in trade and other receivables Number of instruments outstanding, beginning balance (in shares) Number of instruments outstanding, ending balance (in shares) Number of other equity instruments outstanding in share-based payment arrangement BSA-2025-1 BSA-2025-1 [Member] BSA-2025-1 Kreos & Claret financing, tranche C Kreos & Claret Financing, Tranche C [Member] Kreos & Claret Financing, Tranche C FAIR VALUE OF THE UNDERLYING SHARE (in euro per share) Underlying Share Fair Value, Other Equity Instruments Granted Underlying Share Fair Value, Other Equity Instruments Granted Disclosure of financial liabilities [table] Disclosure of financial liabilities [table] Disclosure of main data and assumptions used for the measurement of convertible loan notes Disclosure Of Indirect Measurement Of Convertible Loans Instruments [Table Text Block] Disclosure of breakdown of operating income Disclosure Of Detailed Information Of Operating Income Explanatory [Table Text Block] Disclosure Of Detailed Information Of Operating Income Explanatory Entity Address, City or Town Entity Address, City or Town Operating expenses, development of new indications for obefazimod Operating Expenses, Development Of New Indications For Obefazimod Operating Expenses, Development Of New Indications For Obefazimod Probability-weighted present value of shortfall payment, final redemption Final Redemption, Probability-Weighted Present Value Of Shortfall Payment, Measurement Input [Member] Final Redemption,Probability-Weighted Present Value Of Shortfall Payment, Measurement Input Probability-weighted fair value of tranche A-B warrants with MRI Final Redemption, Probability-Weighted Fair Value With MRI , Measurement Input [Member] Final Redemption, Probability-Weighted Fair Value With MRI , Measurement Input SHARE CAPITAL Issued capital Issued capital [member] Geographical areas [axis] Geographical areas [axis] AGA-2024-3 AGA-2024-3 [Member] AGA-2024-3 Employees Disclosure of information about employees [text block] Liabilities arising from financing activities at beginning of period Liabilities arising from financing activities at end of period Liabilities arising from financing activities Kreos & Claret Financing, Tranche B and C Kreos & Claret Financing, Tranche B and C [Member] Kreos & Claret Financing, Tranche B and C Disclosure of quantitative information about right-of-use assets [table] Disclosure of quantitative information about right-of-use assets [table] Number of warrants repurchased (in shares) Number Of Warrants Repurchased Number Of Warrants Repurchased CIR Tax Year [Axis] CIR Tax Year [Axis] CIR Tax Year Notice accounts Other cash and cash equivalents FURNITURE AND COMPUTER EQUIPMENT Furniture And Computer Equipment [Member] Furniture And Computer Equipment Number of ordinary shares issued (in shares) Increase in number of shares issued (in shares) Increase (decrease) in number of ordinary shares issued Advances related to CRO contracts Non-Current Advances To CRO Contracts Non-Current Advances To CRO Contracts AGA-2025-1, AGA-2025-2, AGA-2025-3, AGA-2025-4, AGA-2025-6 and AGA-2025-7 AGA-2025-1, AGA-2025-2, AGA-2025-3, AGA-2025-4, AGA-2025-6 and AGA-2025-7 [Member] AGA-2025-1, AGA-2025-2, AGA-2025-3, AGA-2025-4, AGA-2025-6 and AGA-2025-7 Intangible assets Intangible assets other than goodwill at beginning of period Intangible assets other than goodwill at end of period Intangible assets other than goodwill Advances related to CRO contracts Current Advances To CRO Contracts Current Advances To CRO Contracts The Group Disclosure of general information about financial statements [text block] Derivative instruments Non-current derivative financial liabilities Disposal Disposals, intangible assets other than goodwill Increase in financial liabilities Increase (Decrease) Through Amortization Cost Remeasurement, Liabilities Arising From Financing Activities Increase (Decrease) Through Amortization Cost Remeasurement, Liabilities Arising From Financing Activities Cash and cash equivalents Cash and cash equivalents at the beginning of the year Cash and cash equivalents at the end of the year Cash and cash equivalents Cash and cash equivalents Probability-weighted fair value of tranche A-B warrants without MRI Final Redemption, Probability-Weighted Fair Value Without MRI , Measurement Input [Member] Final Redemption, Probability-Weighted Fair Value Without MRI , Measurement Input Other receivables and assets Total non-current other receivables and assets Other non-current non-financial assets EQUIPMENT Machinery [member] Disclosure of maturity analysis for derivative financial liabilities [table] Disclosure of maturity analysis for derivative financial liabilities [table] Prepaid expenses Current prepaid expenses Translation reserve Reserve of exchange differences on translation Disclosure of non-adjusting events after reporting period [line items] Disclosure of non-adjusting events after reporting period [line items] ASSETS Assets [abstract] ROU Right-of-use assets [member] Credit spread Credit spread, measurement input [member] TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY Equity and liabilities United States UNITED STATES Property, plant and equipment [abstract] Retained earnings Retained earnings, excluding profit (loss) for reporting period Registered direct offering Registered Direct Offering [Member] Registered Direct Offering Current assets Current assets [abstract] Board Member Board Member [Member] Board Member Other Other current payables Entity Address, Postal Zip Code Entity Address, Postal Zip Code Revenue [abstract] Non-current assets Non-current assets [abstract] Advances made to (reimbursed by) contract research organizations Advances Made To (Reimbursed By) Contract Research Organizations Advances Made To (Reimbursed By) Contract Research Organizations Kreos A & B BSA Kreos A & B BSA [Member] Kreos A & B BSA Kreos/Claret bond loans Other Kreos, Claret Bond Loans [Member] Other Kreos, Claret Bond Loans Financial liabilities-current portion Current Financial Liabilities [Member] Current Financial Liabilities Acquisition Additions other than through business combinations, property, plant and equipment including right-of-use assets General and administrative General and administrative expense Increase in employer contributions, share-based payments Increase (Decrease) In Employer Contributions, Share-Based Payments Increase (Decrease) In Employer Contributions, Share-Based Payments Income tax Disclosure of income tax [text block] Interest rate Interest rate, measurement input [member] Tax and employee-related payables TAX AND EMPLOYEE-RELATED PAYABLES Current Tax And Employee Benefit Liabilities Current Tax And Employee Benefit Liabilities Disclosure of defined benefit plans [abstract] Disclosure of defined benefit plans [abstract] Early redemption amount (put event) Early Redemption Amount, Measurement Input [Member] Early Redemption Amount, Measurement Input Disclosure of attribution of expenses by nature to their function [table] Disclosure of attribution of expenses by nature to their function [table] Decrease in fair value (Increase) / decrease in derivatives fair value Gains on change in fair value of derivatives BSA-2017-1 BSA-2017-1 [Member] BSA-2017-1 Disclosure of other receivables and other assets Disclosure Of Detailed Information About Other Receivables And Other Assets [Table Text Block] Disclosure Of Detailed Information About Other Receivables And Other Assets Disclosure of remaining contractual maturities of non-derivative financial liabilities Disclosure of maturity analysis for non-derivative financial liabilities [text block] BSA-2024-2 BSA-2024-2 [Member] BSA-2024-2 Heights convertible notes Heights Convertible Notes [Member] Heights Convertible Notes Par value per share (in euro per share) Share Price Share Price Interest paid Interest paid, classified as financing activities Expense relating to short-term leases Expense Relating To Short-Term Leases And Low Value Assets For Which Recognition Exemption Has Been Used Expense Relating To Short-Term Leases And Low Value Assets For Which Recognition Exemption Has Been Used Interest on royalty certificates Interest Expense On Royalty Certificates Interest Expense On Royalty Certificates Employee-related payables Short-term employee benefits accruals Initial price limit, (in euro per share) Initial Price Limit, Measurement Input [Member] Initial Price Limit, Measurement Input Non cash changes : Effect of the change in foreign currency exchange rates Increase (decrease) through effect of changes in foreign exchange rates, liabilities arising from financing activities Credit notes Current Receivables From Credit Notes Current Receivables From Credit Notes SOFTWARE Computer software [member] United States of America, Dollars United States of America, Dollars Financial assets and liabilities Disclosure of fair value of financial instruments [text block] Number of probability-weighted scenarios Number Of Probability-Weighted Scenarios Number Of Probability-Weighted Scenarios Number of outstanding warrants (in shares) Number Of Warrants Outstanding Number Of Warrants Outstanding Cash Cash Related party transactions [abstract] Related party transactions [abstract] Convertible loan notes Convertible Loans Notes [Member] Convertible Loans Notes FAIR VALUE OF THE BSA ( in euro per share) FAIR VALUE OF THE AGA (in euro per share) Equity Instrument Fair Value, Other Equity Instruments Granted Equity Instrument Fair Value, Other Equity Instruments Granted Categories of financial liabilities [domain] Categories of financial liabilities [domain] LONGER THAN 5 YEARS Later than five years [member] Cash flows provided by (used in) investing activities Cash flows from (used in) investing activities [abstract] Increase (decrease) in carrying value resulting from a reasonably possible decrease in unobservable input liabilities Increase (Decrease) In Carrying Value Due To Reasonably Possible Decrease In Unobservable Input Liabilities Increase (Decrease) In Carrying Value Due To Reasonably Possible Decrease In Unobservable Input Liabilities Related parties Disclosure of related party [text block] Intangible assets Disclosure of intangible assets [text block] AGA-2024-1 AGA-2024-1 [Member] AGA-2024-1 Statement of compliance Statement of IFRS compliance [text block] VAT receivables Current value added tax receivables Disposal Disposals, property, plant and equipment including right-of-use assets Non-cash changes: conversion into shares Increase (Decrease) Through Conversion Into Shares, Liabilities Arising From Financing Activities Increase (Decrease) Through Conversion Into Shares, Liabilities Arising From Financing Activities Interest expense on lease liabilities Interest on lease liabilities Interest expense on lease liabilities Kreos & Claret Financing, Tranche A-B Kreos & Claret Financing, Tranche A-B [Member] Kreos & Claret Financing, Tranche A-B AGA-2023-3 AGA-2023-3 [Member] AGA-2023-3 Shares based compensation expense Increase (decrease) through share-based payment transactions, equity Reconciliation of number of shares outstanding [abstract] Reconciliation of number of shares outstanding [abstract] Decrease Decrease In Lease Liabilities Decrease In Lease Liabilities Number of free shares plans issued Number Of Free Shares Plans Issued Number Of Free Shares Plans Issued Disclosure of classes of share capital [table] Disclosure of classes of share capital [table] Unobservable inputs [axis] Unobservable inputs [axis] Use of judgments and estimates Disclosure Of Accounting Policy For Accounting Judgements And Estimates Explanatory [Policy Text Block] Disclosure Of Accounting Policy For Accounting Judgements And Estimates Explanatory Foreign currency translation differences Other comprehensive income, net of tax, exchange differences on translation of foreign operations Total non-current assets Non-current assets Disclosure of maturity analysis for derivative financial liabilities [line items] Disclosure of maturity analysis for derivative financial liabilities [line items] Financial Agreement [Domain] Financial Agreement [Domain] Financial Agreement [Domain] Convertible loan notes Non-Current Convertible Loans Notes Non-Current Convertible Loans Notes Classes of property, plant and equipment [axis] Classes of property, plant and equipment [axis] Minimal return Minimal Return, Measurement Input [Member] Minimal Return, Measurement Input Number of countries Number Of Countries Number Of Countries Exercise of warrants Proceeds from exercise of warrants Contribution to Group's net profits (losses), percentage Contribution To Group's Net Profits (Losses), Percentage Contribution To Group's Net Profits (Losses), Percentage Classes of property, plant and equipment [domain] Classes of property, plant and equipment [domain] Cash-generating units [axis] Cash-generating units [axis] Disclosure Of Other Receivables And Other Assets [Table] Disclosure Of Other Receivables And Other Assets [Table] Disclosure Of Other Receivables And Other Assets [Table] Entity Address, Country Entity Address, Country Convertible loans notes, undiscounted cash flows Convertible Loans Notes, Undiscounted Cash Flows Convertible Loans Notes, Undiscounted Cash Flows Other receivables and assets Disclosure of trade and other receivables [text block] Reconciliation of changes in intangible assets other than goodwill [abstract] Reconciliation of changes in intangible assets other than goodwill [abstract] Other financial assets Total other current financial assets Other current financial assets Exercises of share warrants (in shares) Increase (Decrease) In Number Of Shares Issued Through Exercise Of Share Warrants Increase (Decrease) In Number Of Shares Issued Through Exercise Of Share Warrants Euro Euro Member Countries, Euro Tranche C Tranche C [Member] Tranche C Major ordinary share transactions Major ordinary share transactions [member] Dosage [Axis] Dosage [Axis] Dosage Increase / (decrease) in other liabilities / (assets) at amortized cost Losses On Financial Liabilities At Amortized Cost Losses On Financial Liabilities At Amortized Cost Wittycel SAS Wittycel SAS - ABX196 [Member] Wittycel SAS - ABX196 Amount of reasonably possible decrease in unobservable input, liabilities Amount Of Reasonably Possible Decrease In Unobservable Input, Liabilities Amount Of Reasonably Possible Decrease In Unobservable Input, Liabilities AGA-2023-4 AGA-2023-4 [Member] AGA-2023-4 Effect of movements in exchange rates on cash held Foreign exchange gain (loss) Effect of exchange rate changes on cash and cash equivalents Interest received Interest received, classified as investing activities Held to maturity scenario probability Voluntary Conversion Scenario Probability, Measurement Input [Member] Voluntary Conversion Scenario Probability, Measurement Input Cash flows provided by (used in) operating activities Cash flows from (used in) operating activities Payments for debt issue costs Payments for debt issue costs Disclosure of terms and conditions of share-based payment arrangement [line items] Disclosure of terms and conditions of share-based payment arrangement [line items] Non-current liabilities Non-current liabilities [abstract] Non-cash changes: classification of embedded derivatives as separate derivative financial instruments Increase (Decrease) Through Classification of Embedded Derivatives as Separate Financial Instruments, Liabilities Arising From Financing Activities Increase (Decrease) Through Classification of Embedded Derivatives as Separate Financial Instruments, Liabilities Arising From Financing Activities Kreos & Claret BSA Kreos & Claret Financing, BSA [Member] Kreos & Claret Financing, BSA Share-based payments Disclosure of share-based payment arrangements [text block] Kreos & Claret financing Kreos & Claret Financing [Member] Kreos & Claret Financing Kreos A-B and C Kreos A-B And C [Member] Kreos A-B And C BSA-2024-1 BSA-2024-1 [Member] BSA-2024-1 Disclosure of detailed information about financial instruments [table] Disclosure of detailed information about financial instruments [table] Intellectual property fees Intellectual Property Fees Intellectual Property Fees Geographical areas [domain] Geographical areas [domain] Monte Carlo model Monte Carlo Model [Member] Monte Carlo Model Royalty certificates Royalty Certificates [Member] Royalty Certificates Clinical Trial Program [Domain] Clinical Trial Program [Domain] Clinical Trial Program [Domain] Document Period End Date Document Fiscal Year Focus Adjustments for: Adjustments to reconcile profit (loss) [abstract] Management and assessment of financial risks Disclosure of financial risk management [text block] Borrowings, number of tranches Borrowings, Number Of Tranches Borrowings, Number Of Tranches Discount rate Unobservable Input, Liabilities, Discount Rate Unobservable Input, Liabilities, Discount Rate Transaction costs related to capital increase Share Issue Related Cost (Credit) Share Issue Related Cost (Credit) Favorable change in exchange rate, impact on foreign exchange gain Sensitivity Analysis For Types Of Market Risk, 10% Favorable Change in Exchange Rate, Impact On Foreign Exchange Gain (Loss) Sensitivity Analysis For Types Of Market Risk, 10% Favorable Change in Exchange Rate, Impact On Foreign Exchange Gain (Loss) Decrease in financial liabilities at fair value Increase (decrease) in financial liabilities at fair value due to reasonably possible increase in unobservable input Increase (decrease) in fair value measurement due to reasonably possible increase in unobservable input, liabilities Disclosure of attribution of expenses by nature to their function [line items] Disclosure of attribution of expenses by nature to their function [line items] Current financial liabilities Current financial liabilities Financial expenses Financial expenses Finance costs VOLATILITY Expected Volatility, Other Equity Instruments Granted Expected Volatility, Other Equity Instruments Granted Disclosure of other financial assets Disclosure of financial assets [text block] Non-cash changes : subsidies Increase (Decrease) Through Subsidies, Liabilities Arising From Financing Activities Increase (Decrease) Through Subsidies, Liabilities Arising From Financing Activities Other receivables and assets Other Receivables And Assets [Member] Other Receivables And Assets Other operating income Total operating income Other income Disclosure of credit risk exposure [table] Disclosure of credit risk exposure [table] Non-cash changes: amortized cost remeasurement Increase (Decrease) Through Amortized Cost Remeasurement, Liabilities Arising From Financing Activities Increase (Decrease) Through Amortized Cost Remeasurement, Liabilities Arising From Financing Activities Accounting principles Disclosure of material accounting policy information [text block] Maximum drawdown capacity Other Financial Liabilities, Maximum Drawdown Capacity Other Financial Liabilities, Maximum Drawdown Capacity Foreign exchange gains Foreign exchange gain Trade payables Current trade payables AGA-2023-2 AGA-2023-2 [Member] AGA-2023-2 Adverse change in exchange rate, impact on foreign exchange loss Sensitivity Analysis For Types Of Market Risk, 10% Adverse Change in Exchange Rate, Impact On Foreign Exchange Gain (Loss) Sensitivity Analysis For Types Of Market Risk, 10% Adverse Change in Exchange Rate, Impact On Foreign Exchange Gain (Loss) Warrants [Domain] Warrants [Domain] Warrants Entity Central Index Key Entity Central Index Key Items that are or may be reclassified subsequently to profit or loss Other comprehensive income that will be reclassified to profit or loss, net of tax Cash and cash equivalents Disclosure of cash and cash equivalents [text block] Other financial expense Other finance cost Derivative financial liabilities at beginning of period Derivative financial liabilities at end of period Derivative instruments Derivative financial liabilities Prepaid expenses - non current Non-Current Prepaid Expenses Non-Current Prepaid Expenses Disclosure of credit risk exposure [line items] Disclosure of credit risk exposure [line items] Consulting and professional fees Professional fees expense Valuation techniques used in fair value measurement [axis] Valuation techniques used in fair value measurement [axis] Contribution to Group's assets, percentage Contribution To Group's Assets, Percentage Contribution To Group's Assets, Percentage Number of participating clinical trial sites Number Of Participating Clinical Trial Sites Number Of Participating Clinical Trial Sites Ordinary shares Ordinary shares [member] POS Probability Of Success, Measurement Input [Member] Probability Of Success, Measurement Input Increase in deposits Cash Payments For Deposits Cash Payments For Deposits Interest on convertible loan notes Interest expense on debt instruments issued Income (loss) per share Disclosure of earnings per share [text block] GROSS VALUES Gross carrying amount [member] Disclosure of average workforce during the periods Disclosure Of Average Number Of Employees [Table Text Block] Disclosure Of Average Number Of Employees Trade payables and other current liabilities Trade payables and other current liabilities Trade and other current payables LIABILITIES AND SHAREHOLDERS' EQUITY Equity and liabilities [abstract] Warrants [Axis] Warrants [Axis] Warrants Foreign exchange losses Foreign Exchange Losses Foreign Exchange Losses1 Proceeds from government grants Proceeds from government grants, classified as financing activities Accrued invoices Accruals classified as current Reconciliation of changes in property, plant and equipment [abstract] Reconciliation of changes in property, plant and equipment [abstract] Discounted cash flow Discounted cash flow [member] Expected proceeds from share issuance Expected Proceeds From Share Issuance Expected Proceeds From Share Issuance Capital increases Proceeds from issuing shares FROM 2 TO 5 YEARS Later than two years and not later than five years [member] LESS THAN 1 YEAR Not later than one year [member] Prosynergia Prosynergia [Member] Prosynergia Number of patients achieving clinical response Number Of Patients Achieving Clinical Response Number Of Patients Achieving Clinical Response BCE-2018-1 BCE-2018-1 [Member] BCE-2018-1 Operating loss Profit (loss) from operating activities Increase in professional fees expense Increase (Decrease) In Professional Fees Expense Increase (Decrease) In Professional Fees Expense BCE-2017-4 BCE-2017-4 [Member] BCE-2017-4 Royalty certificates, undiscounted cash flows Royalty Certificates, Undiscounted Cash Flows Royalty Certificates, Undiscounted Cash Flows LIABILITIES AT FAIR VALUE THROUGH PROFIT AND LOSS Financial liabilities at fair value through profit or loss, category [member] Financial liabilities-non current portion Non-Current Financial Liabilities [Member] Non-Current Financial Liabilities Long-term advances made to CROs Non-Current Advances To CRO Contracts [Member] Non-Current Advances To CRO Contracts Percentage of reasonably possible decrease in unobservable input, liabilities Percentage of reasonably possible decrease in unobservable input, liabilities Entity Address, Address Line One Entity Address, Address Line One Disclosure of financial assets [line items] Disclosure of financial assets [line items] Property, plant and equipment Property, plant and equipment [member] Proceeds from borrowings Proceeds from borrowings, classified as financing activities Payments of the lease liabilities Payments of lease liabilities, classified as financing activities Fair Value Measurement [Abstract] Fair Value Measurement [Abstract] Issuance Issuance Of Derivative Instruments Issuance Of Derivative Instruments Non-cash changes: other fair value remeasurement Increase (decrease) through changes in fair values, liabilities arising from financing activities Effect of unwinding the discount related to advances Adjustments For Unwinding Of Discount Related To Conditional Advances Adjustments For Unwinding Of Discount Related To Conditional Advances Elimination of retirement benefit obligations Adjustments for increase (decrease) in employee benefit liabilities Increase in fair value (Increase) / decrease in derivatives fair value Losses on change in fair value of derivatives Conditional advances Bpifrance Banque Publique d’Investissement (BPI) [Member] Banque Publique d’Investissement (BPI) Disclosure of breakdown of the compensation expenses Explanation of effect of share-based payments on entity's profit or loss [text block] Share-Based Payment Arrangements [Abstract] Share-Based Payment Arrangements [Abstract] Share-Based Payment Arrangements [Abstract] Ordinary share price (in euro per share) Share price Share Price, Measurement Input [Member] Share Price, Measurement Input BCE-2017-5 BCE-2017-5 [Member] BCE-2017-5 Entity Registrant Name Entity Registrant Name Basic loss per share (in euro per share) Basic earnings (loss) per share AGA-2023-1 AGA-2023-1 [Member] AGA-2023-1 Change in provisions, deferred income and other liabilities Adjustments For Increase (Decrease) In Provisions, Deferred Income And Other Liabilities Adjustments For Increase (Decrease) In Provisions, Deferred Income And Other Liabilities Measurement [axis] Measurement [axis] Number of enrolled patients Number Of Patients Number Of Patients Statement of cash flows [abstract] Disclosure Of Operating Income [Table] Disclosure Of Operating Income [Table] Disclosure Of Operating Income [Table] Weighted average number of outstanding shares used for computing diluted loss per share (in shares) Weighted average number of outstanding shares, diluted loss per share (in shares) Weighted average number of ordinary shares used in calculating diluted earnings per share Disclosure of financial assets [table] Disclosure of financial assets [table] Maximum number of shares to be issued if all conditions are met (in shares) Maximum Number Of Other Equity Instruments To Be Issued In Share-Based Payment Arrangement If All Conditions Are Met Maximum Number Of Other Equity Instruments To Be Issued In Share-Based Payment Arrangement If All Conditions Are Met Title and Position [Domain] Title and Position [Domain] Number of instruments exercisable (in shares) Number of other equity instruments exercisable in share-based payment arrangement Transaction costs Transaction Costs Transaction Costs Decrease in financial assets at fair value Increase (decrease) in fair value measurement due to reasonably possible increase in unobservable input, assets Increase (decrease) in fair value measurement due to reasonably possible increase in unobservable input, assets Intangible assets other than goodwill [member] Classes of intangible assets other than goodwill [domain] Counterparty Name [Domain] Counterparty Name [Domain] Elimination of share-based compensation expenses Adjustments for share-based payments BSA-2025-2 BSA-2025-2 [Member] BSA-2025-2 ABTECT-1 and ABTECT-2 ABTECT-1 and ABTECT-2 [Member] ABTECT-1 and ABTECT-2 Pooled placebo-adjusted clinical response rate Pooled Placebo-Adjusted Clinical Response Rate Pooled Placebo-Adjusted Clinical Response Rate Current liabilities Current liabilities [abstract] Other financial assets Other Financial Assets [Member] Other Financial Assets Retirement benefit obligations Disclosure of employee benefits [text block] Deposits Long-term deposits Increase / (decrease) in other liabilities (assets) at fair value through profit and loss Gains On Financial Liabilities At Fair Value Through Profit Or Loss Gains On Financial Liabilities At Fair Value Through Profit Or Loss Borrowings, fixed conversion price (euro per share) Borrowings, Fixed Conversion Price Borrowings, Fixed Conversion Price Proceeds from research tax credit Proceeds From Research Tax Credit Proceeds From Research Tax Credit All Currencies [Domain] All Currencies [Domain] Shareholders’ equity Equity [abstract] Other tax and related payments Current Payables On Other Tax And Related Payments Current Payables On Other Tax And Related Payments Disclosure of operating segments [abstract] Disclosure of carrying amounts and fair value of financial assets Disclosure of fair value measurement of assets [text block] Subclassifications of assets, liabilities and equities [abstract] Tranches [Axis] Tranches [Axis] Tranches Amortized cost (EIR method) Amortized Cost (EIR Method) [Member] Amortized Cost (EIR Method) Classes of share capital [domain] Classes of share capital [domain] AGA-2024-4 AGA-2024-4 [Member] AGA-2024-4 Probability-weighted present value of shortfall payment, tender offer Tender Offer, Probability-Weighted Present Value Of Shortfall Payment, Measurement Input [Member] Tender Offer, Probability-Weighted Present Value Of Shortfall Payment, Measurement Input Financial income Adjustments For Other Finance Income Adjustments For Other Finance Income Kreos C BSA Kreos C BSA [Member] Kreos C BSA Acquisition Additions other than through business combinations, intangible assets other than goodwill Proceeds from issue of ordinary shares Proceeds from issue of ordinary shares Disclosure Of Operating Income [Line Items] Disclosure Of Operating Income [Line Items] Disclosure Of Operating Income [Line Items] Financial income Financial income Finance income Tranche B Tranche B [Member] Tranche B Classes of financial liabilities [axis] Classes of financial liabilities [axis] Classes of financial liabilities [domain] Classes of financial liabilities [domain] Interest expenses and other financial expenses Adjustments For Other Finance Costs Adjustments For Other Finance Costs BCE-2017-1 BCE-2017-1 [Member] BCE-2017-1 Issue of free shares (in shares) Number Of Free Shares Issued Number Of Free Shares Issued Kreos & Claret financing, tranche B Kreos & Claret Financing, Tranche B [Member] Kreos & Claret Financing, Tranche B Average number of employees Average number of employees BCE-2018-4 BCE-2018-4 [Member] BCE-2018-4 Number of treasury shares held (in shares) Number Of Treasury Shares Held Number Of Treasury Shares Held Sale Of Stock [Axis] Sale Of Stock [Axis] Sale Of Stock Other receivables and assets Total current other receivables and assets Current Receivables And Current Prepaid Expenses Current Receivables And Current Prepaid Expenses Dosage [Domain] Dosage [Domain] Dosage [Domain] Lease liabilities at beginning of period Lease liabilities at end of period Lease liabilities Lease liabilities Disclosure of financial assets [abstract] Transactions on treasury shares Increase (decrease) through treasury share transactions, equity Types of contracts [axis] Types of contracts [axis] Non-cash changes: interest expense and other Increase (decrease) through other changes, liabilities arising from financing activities Advances reimbursed by / (made to) CROs Payments For Advances Reimbursed (Made to) Contract Research Organizations Payments For Advances Reimbursed (Made to) Contract Research Organizations PREMIUMS RELATED TO SHARE CAPITAL Share premium [member] Lease liability, percentage of total Lease Liability, Percentage Of Total Lease Liability, Percentage Of Total Other Miscellaneous Other Operating Income, Including Adjustments Miscellaneous Other Operating Income, Including Adjustments AGA-2025-7 AGA-2025-7 [Member] AGA-2025-7 Disount rate applied to long-term advances Discount Rate Applied To Long-Term Advances Discount Rate Applied To Long-Term Advances Off-Balance Sheet Commitments [Abstract] Off-Balance Sheet Commitments Royalty certificates Non-Current Royalty Certificates Non-Current Royalty Certificates Minimum Minimum [Member] Liabilities arising from financing activities [domain] Liabilities arising from financing activities [domain] Principal Agreements [Axis] Principal Agreements [Axis] Principal Agreements Disclosure of reconciliation of other equity instruments Disclosure of number and weighted average exercise prices of other equity instruments [text block] Volatility, expiry Volatility For Shares Measurement Input, Expiry [Member] Volatility For Shares Measurement Input, Expiry ABTECT-1 ABTECT-1 [Member] ABTECT-1 Financial liabilities Liabilities Liabilities Share capital Issued capital Disclosure of reconciliation of liabilities arising from financing activities [line items] Disclosure of reconciliation of liabilities arising from financing activities [line items] Percentage of conditional advances waived Percentage Of Conditional Advances Waived Percentage Of Conditional Advances Waived Exclusive licensing agreement with CNRS, University of Montpellier and Institut Curie Exclusive Licensing Agreement With CNRS, University Of Montpellier And Institut Curie [Member] Exclusive Licensing Agreement With CNRS, University Of Montpellier And Institut Curie Categories of financial assets [axis] Categories of financial assets [axis] Disclosure of remaining contractual maturities of derivative financial liabilities Disclosure of maturity analysis for derivative financial liabilities [text block] Title and Position [Axis] Title and Position [Axis] Borrowings, maximum borrowing capacity per tranche Borrowings, Maximum Borrowing Capacity Per Tranche Borrowings, Maximum Borrowing Capacity Per Tranche CIR Tax Year [Domain] CIR Tax Year [Domain] CIR Tax Year [Domain] Number of shares outstanding (in shares) Number of shares outstanding BSAs Total BSAs Share Subscription Warrants (BSA) [Member] Share Subscription Warrants (BSA) Number of operating segments Number Of Operating Segments Number Of Operating Segments Issue of share warrants Increase (Decrease) Through Issuance of Warrants, Equity Increase (Decrease) Through Issuance of Warrants, Equity Other financial assets Disclosure of other assets [text block] Increase / (decrease) in trade payables Adjustments for increase (decrease) in trade accounts payable Total financial liabilities Financial liabilities Interest on bond loans Interest expense on bonds Repayments of convertible loan notes Repayments Of Convertible Loans Notes Repayments Of Convertible Loans Notes Income tax Tax expense (income) Lease liabilities Lease liabilities [member] Significant unobservable input, liabilities Significant unobservable input, liabilities Cash-generating units [domain] Cash-generating units [domain] Convertible loan notes Current Portion Of Non-Current Convertible Loans Notes Current Portion Of Non-Current Convertible Loans Notes Repayment of PGE Repayments Of PGE Repayments Of PGE SUBSCRIPTION PRICE (in euro per share) Equity Instrument Price, Other Equity Instruments Granted Equity Instrument Price, Other Equity Instruments Granted Significant events for the year ended December 31, 2024 and the nine-month period ended September 30, 2025 and subsequent events Disclosure Of Significant Events For The Period Reported And Events After Reporting Period [Text Block] Disclosure Of Significant Events For The Period Reported And Events After Reporting Period Disclosure of variation in lease liabilities Disclosure Of Leases For Lessee [Table Text Block] Disclosure Of Leases For Lessee Cash flows provided by (used in) operating activities Cash flows from (used in) operating activities [abstract] Off-balance sheet commitments received and contingent assets Disclosure of other provisions, contingent liabilities and contingent assets [text block] Disclosure Of Fair Value Measurement Of Assets And Liabilities [Table] Disclosure Of Fair Value Measurement Of Assets And Liabilities [Table] Disclosure Of Fair Value Measurement Of Assets And Liabilities BSA-2015-11 BSA-2015-11 [Member] BSA-2015-11 Non-cash changes: (gain)/loss on recognition or derecognition Increase (Decrease) Through Gain (Loss) On Recognition/Derecognition, Liabilities Arising From Financing Activities Increase (Decrease) Through Gain (Loss) On Recognition/Derecognition, Liabilities Arising From Financing Activities Dividend Expected Dividend, Measurement Input [Member] Expected Dividend, Measurement Input Property, plant and equipment Property, plant and equipment including right-of-use assets at beginning of period Property, plant and equipment including right-of-use assets at end of period Property, plant and equipment including right-of-use assets Financial liabilities, at fair value Financial liabilities, at fair value Current Fiscal Year End Date Document Period End Date Share-based compensation expense Expense from equity-settled share-based payment transactions Non-adjusting events after reporting period [axis] Non-adjusting events after reporting period [axis] Non-adjusting events after reporting period [domain] Non-adjusting events after reporting period [domain] 7-year expiry scenario probability Expiry Scenario Probablity, Measurement Input [Member] Expiry Scenario Probablity, Measurement Input Disclosure of classes of share capital [line items] Disclosure of classes of share capital [line items] Collaboration agreements, development milestone payment, Phase 2 Collaboration Agreements, Development Milestone Payment, Phase 2 Collaboration Agreements, Development Milestone Payment, Phase 2 Valuation techniques used in fair value measurement [domain] Valuation techniques used in fair value measurement [domain] Goodwill and impairment test Disclosure of goodwill [text block] Effect of unwinding the discount related to advances made to CROs Unwinding Effect Of Discount Related To Advances Made To CROs Unwinding Effect Of Discount Related To Advances Made To CROs Maturity [axis] Maturity [axis] Other Other inflows (outflows) of cash, classified as financing activities Top of range Top of range [member] Intangible assets and goodwill [abstract] Classes of financial instruments [axis] Classes of financial instruments [axis] Research and development Research and development expense Goodwill Goodwill Other financial liabilities Other Financial Liabilities [Member] Other Financial Liabilities Impact of the Ukraine/Russia Hostilities on the Group Disclosure Of Impact Of The Ukraine/Russia Hostilities On The Group [Policy Text Block] Disclosure Of Impact Of The Ukraine/Russia Hostilities On The Group Operating expenses, CD program Operating Expenses, CD Program Operating Expenses, CD Program Increase / (decrease) in tax and social security liabilities Adjustments For Increase (Decrease) In Tax And Social Security Liabilities Adjustments For Increase (Decrease) In Tax And Social Security Liabilities Actuarial gains and losses on retirement benefit obligations Other comprehensive income, net of tax, gains (losses) on remeasurements of defined benefit plans Document Type Document Type Operating expenses, transversal activities Operating Expenses, Transversal Activities Operating Expenses, Transversal Activities Gross lease liabilities Gross lease liabilities Royalty certificate, percentage of future sales Royalty Certificate, Percentage Of Future Sales Royalty Certificate, Percentage Of Future Sales Other sales and marketing expenses Other research and development expenses Other general and administrative expenses Miscellaneous other operating expense Net proceeds from non-convertible bond loans Net Proceeds From Non-Convertible Loans Notes Net Proceeds From Non-Convertible Loans Notes Financial Agreement [Axis] Financial Agreement [Axis] Financial Agreement Items that will not be reclassified to profit or loss Other comprehensive income that will not be reclassified to profit or loss, net of tax Disclosure Of Cash And Cash Equivalents [Line Items] Disclosure Of Cash And Cash Equivalents [Line Items] Disclosure Of Cash And Cash Equivalents [Line Items] Accounting Principles [Abstract] Accounting Principles [Abstract] Accounting Principles [Abstract] Profit or loss [abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] Disclosure of financial liabilities [abstract] Disclosure of financial liabilities [abstract] Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis] Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis] Technology- based intangible assets, assets acquisitions Technology- Based Intangible Assets, Assets Acquisitions Technology- Based Intangible Assets, Assets Acquisitions Net proceeds from issuance of ordinary shares Net Proceeds From Issue Of Ordinary Shares Net Proceeds From Issue Of Ordinary Shares Conversion of convertible instruments (in shares) Increase (Decrease) In Number Of Shares Issued Through Conversion Of Convertible Instruments Increase (Decrease) In Number Of Shares Issued Through Conversion Of Convertible Instruments Classes of assets [axis] Classes of assets [axis] Disclosure of changes in derivative instruments Disclosure Of Changes In Derivative Financial Instruments [Table Text Block] Disclosure Of Changes In Derivative Financial Instruments Borrowings by name [domain] Borrowings by name [domain] Types of share-based payment arrangements [domain] Types of share-based payment arrangements [domain] Other equity agreements Other Equity Agreements [Member] Other Equity Agreements Currency risk Currency risk [member] Vesting period Vesting Requirements For Share-Based Payment Arrangement, Vesting Period Vesting Requirements For Share-Based Payment Arrangement, Vesting Period France FRANCE Earnings per share [abstract] Conditional advances Bpifrance Conditional Advances [Member] Conditional Advances Range [axis] Range [axis] Components of equity [axis] Components of equity [axis] CARENA conditional advance CARENA Conditional Advance, BPI [Member] CARENA Conditional Advance, BPI Disclosure of financial liabilities breakdown Disclosure of financial liabilities [text block] Disclosure of financial liabilities [line items] Disclosure of financial liabilities [line items] AGAs Total AGAs Share Subscription Warrants (AGA) [Member] Share Subscription Warrants (AGA) Net loss before tax Profit (loss) before tax Property, plant and equipment including right-of-use assets [axis] Property, plant and equipment including right-of-use assets [axis] Other comprehensive income (loss) Other comprehensive income (loss) Other comprehensive income Classes of liabilities [axis] Classes of liabilities [axis] Operating expenses, UC clinical program Operating Expenses, UC Clinical Program Operating Expenses, UC Clinical Program AGA-2024-2 AGA-2024-2 [Member] AGA-2024-2 Fair value of other equity instruments Aggregate Fair Value, Other Equity Instruments Outstanding Aggregate Fair Value, Other Equity Instruments Outstanding Disclosure Of Cash And Cash Equivalents [Table] Disclosure Of Cash And Cash Equivalents [Table] Disclosure Of Cash And Cash Equivalents [Table] Provisions Current provisions Other current provisions Conditional advances Bpifrance Conditional Advances Conditional Advances Kreos OCABSA Kreos OCABSA [Member] Kreos OCABSA Other Other Non-Current Miscellaneous Financial Assets Other Non-Current Miscellaneous Financial Assets Types of share-based payment arrangements [axis] Types of share-based payment arrangements [axis] Elimination of amortization of intangibles and depreciation of property, plant and equipment Adjustments for depreciation and amortisation expense Shareholders’ equity Disclosure of share capital, reserves and other equity interest [text block] Interest on conditional advances and PGE Interest expense on borrowings Disclosure Of Other Receivables And Other Assets [Line Items] Disclosure Of Other Receivables And Other Assets [Line Items] Disclosure Of Other Receivables And Other Assets [Line Items] Operating income Disclosure of other operating income [text block] Disclosure Of Lease Liabilities [Line Items] Disclosure Of Lease Liabilities [Line Items] Disclosure Of Lease Liabilities [Line Items] Disclosure of carrying amounts and fair value of financial liabilities Disclosure of fair value measurement of liabilities [text block] Capital increase from issuance of ordinary shares Issue of equity Proceeds Increase Through Proceeds, Liabilities Arising From Financing Activities Increase Through Proceeds, Liabilities Arising From Financing Activities Borrowings, undiscounted cash flows Bank borrowings, undiscounted cash flows Repayment of excess conditional advances claimed Repayment Of Excess Conditional Advances Claimed Repayment Of Excess Conditional Advances Claimed Provisions Non-current provisions Other non-current provisions Risk-free rate Risk-Free Interest Rate, Measurement Input [Member] Risk-Free Interest Rate, Measurement Input Percentage of reasonably possible increase in unobservable input, liabilities Percentage of reasonably possible increase in unobservable input, liabilities Net gain on sale of treasury shares Adjustments For Net Gain On Sale Of Treasury Shares Adjustments For Net Gain On Sale Of Treasury Shares Classes of financial instruments [domain] Classes of financial instruments [domain] Effect of the change in foreign currency exchange rates Increase (decrease) through net exchange differences, property, plant and equipment including right-of-use assets Risk-free rate, expiry Risk-Free Interest Rate, Measurement Input, Expiry [Member] Risk-Free Interest Rate, Measurement Input, Expiry ADS American Depository Shares [Member] American Depository Shares Expected proceeds from share issuance, shelf registration Expected Proceeds From Share Issuance, Shelf Registration Expected Proceeds From Share Issuance, Shelf Registration Attribution of expenses by nature to their function [domain] Attribution of expenses by nature to their function [domain] Increase Increase In Lease Liabilities Increase In Lease Liabilities AGAs Free Shares (AGA) [Member] Free Shares (AGA) Increase Depreciation, property, plant and equipment including right-of-use assets Property, plant and equipment including right-of-use assets [domain] Property, plant and equipment including right-of-use assets [domain] Effective interest rate Royalty Certificates, Effective Interest Rate Royalty Certificates, Effective Interest Rate Weighted average number of outstanding shares used for computing basic loss per share (in shares) Weighted average number of outstanding shares, basic loss per share (in shares) Weighted average number of ordinary shares used in calculating basic earnings per share Borrowings by name [axis] Borrowings by name [axis] Borrowings, maximum borrowing capacity Borrowings, Maximum Borrowing Capacity Borrowings, Maximum Borrowing Capacity Payables and other current liabilities Disclosure of trade and other payables [text block] Current advances to suppliers Current advances to suppliers Disclosure of detailed information about intangible assets [table] Disclosure of detailed information about intangible assets [table] Tranche 2 Tranche Two [Member] Tranche Two Disclosure of breakdown of trade and other payables Disclosure Of Breakdown Of Trade And Other Payables [Table Text Block] Disclosure Of Breakdown Of Trade And Other Payables Borrowings Borrowings AGA-2024-7 AGA-2024-7 [Member] AGA-2024-7 Disclosure of expenses by nature Disclosure of expenses by nature [text block] Disclosure of tax and employee-related payables Disclosure Of Tax And Employee-Related Payables Explanatory [Table Text Block] Disclosure Of Tax And Employee-Related Payables Explanatory NET LOSS FOR THE YEAR Retained earnings, profit (loss) for reporting period [member] Disclosure of commitments and contingent liabilities Disclosure of commitments and contingent liabilities [text block] Financial liabilities Disclosure of financial instruments [text block] Disclosure of reconciliation of property, plant and equipment Disclosure of detailed information about property, plant and equipment [text block] Heights convertible notes, tranche A Heights Convertible Notes, Tranche A [Member] Heights Convertible Notes, Tranche A Exercises Exercise Of Derivative Instruments Exercise Of Derivative Instruments LICENSES Licences [member] Cash flows provided by (used in) investing activities Cash flows from (used in) investing activities Increase (decrease) in cash and cash equivalents Increase (decrease) in cash and cash equivalents after effect of exchange rate changes Kreos A & B & C BSA Kreos A & B & C BSA [Member] Kreos A & B & C BSA Minimal return Final Redemption Scenario Probability, Measurement Input [Member] Final Redemption Scenario Probability, Measurement Input Disclosure of detailed information about intangible assets [line items] Disclosure of detailed information about intangible assets [line items] Cash flows provided by (used in) financing activities Cash flows from (used in) financing activities Personnel costs Employee benefits expense Issue of equity, offering price per share (in dollar/euro per share) Issue Of Equity, Offering Price Per Share Issue Of Equity, Offering Price Per Share Increase Amortisation, intangible assets other than goodwill Repurchases Repurchase Of Derivative Instruments Repurchase Of Derivative Instruments Proceeds from issuing other equity instruments Proceeds from issuing other equity instruments PATENTS Copyrights, patents and other industrial property rights, service and operating rights [member] BCE-2016-1 BCE-2016-1 [Member] BCE-2016-1 Changes in working capital requirements Increase (decrease) in working capital Total current assets Current assets AMORTIZATION Accumulated depreciation, amortisation and impairment [member] AGA-2025 AGA-2025 [Member] AGA-2025 Statement of changes in equity [table] Statement of changes in equity [table] RETAINED EARNINGS Retained earnings, excluding profit (loss) for reporting period [member] RNP-VIR conditional advance RNP-VIR Conditional Advance, BPI [Member] RNP-VIR Conditional Advance, BPI Cash flows provided by (used in) operating activities before change in working capital requirements Cash flows from (used in) operations before changes in working capital Issue of free shares Increase (Decrease) From Free Shares Issued Increase (Decrease) From Free Shares Issued Research tax credit ("CIR") Current Research Tax Credit Receivables Current Research Tax Credit Receivables Types of risks [axis] Types of risks [axis] Disclosure Of Warrants Arrangements [Table] Disclosure Of Warrants Arrangements [Table] Disclosure Of Warrants Arrangements Volatility Historical volatility for shares, measurement input [member] Disclosure of net financial income (loss) Disclosure Of Detailed Information About Finance Income (Cost) [Table Text Block] Disclosure Of Detailed Information About Finance Income (Cost) Going concern Description Of Accounting Policy For Going Concern [Policy Text Block] Description Of Accounting Policy For Going Concern Classes of assets [domain] Classes of assets [domain] Document Period End Date Current Fiscal Year End Date Net proceeds from PGE Net Proceeds From Sale Of Royalty Certificates Net Proceeds From Sale Of Royalty Certificates Fair value of convertible notes Aggregate Fair Value, Convertible Notes Aggregate Fair Value, Convertible Notes Disclosure Of Lease Liabilities [Table] Disclosure Of Lease Liabilities [Table] Disclosure Of Lease Liabilities [Table] Cash equivalents Cash equivalents AGA-2024-6 AGA-2024-6 [Member] AGA-2024-6 Disclosure Of Employee Workforce [Table] Disclosure Of Employee Workforce [Table] Disclosure Of Employee Workforce [Table] Financial liabilities, undiscounted cash flows Financial Liabilities, Undiscounted Cash Flows Financial Liabilities, Undiscounted Cash Flows Bottom of range Bottom of range [member] Tranche 3 Tranche Three [Member] Tranche Three Increase/(decrease) in derivatives and liabilities measured at fair value Adjustments for fair value losses (gains) Capital increase from issuance of ordinary shares (in shares) Increase (Decrease) In Number Of Ordinary Shares Issued Through Capital Increase Increase (Decrease) In Number Of Ordinary Shares Issued Through Capital Increase RISK FREE RATE Risk Free Interest Rate, Other Equity Instruments Granted Risk Free Interest Rate, Other Equity Instruments Granted Repayments / (payments) related to capital increase Payments For (Proceeds From) Share Issue Related Costs (Credit) Payments For (Proceeds From) Share Issue Related Costs (Credit) General and administrative expense General And Administrative Expense [Member] General And Administrative Expense Attribution of expenses by nature to their function [axis] Attribution of expenses by nature to their function [axis] LIABILITIES AT AMORTIZED COST Financial liabilities at amortised cost, category [member] Disclosure of detailed information about borrowings [line items] Disclosure of detailed information about borrowings [line items] Income taxes paid (refund) [abstract] Income taxes paid (refund) [abstract] ASSETS AT AMORTIZED COST Financial assets at amortised cost, category [member] Par value per share (in euro per share) Par value per share Disclosure of non-adjusting events after reporting period [table] Disclosure of non-adjusting events after reporting period [table] Property, plant and equipment Disclosure of property, plant and equipment [text block] Repayments Decrease Through Repayments, Liabilities Arising From Financing Activities Decrease Through Repayments, Liabilities Arising From Financing Activities Net loss for the period Net loss for the period Net loss for the period Profit (loss) Amount of reasonably possible increase in unobservable input, liabilities Amount Of Reasonably Possible Increase In Unobservable Input, Liabilities Amount Of Reasonably Possible Increase In Unobservable Input, Liabilities Increase in operating expenses, transversal activities Increase (Decrease) In Operating Expenses, Transversal Activities Increase (Decrease) In Operating Expenses, Transversal Activities Amendment Flag Amendment Flag Components of equity [domain] Components of equity [domain] Risk-free, tender offer Risk-Free Interest Rate, Measurement Input, Tender Offer [Member] Risk-Free Interest Rate, Measurement Input, Tender Offer Total non-current liabilities Non-current liabilities Closing foreign exchange rate Closing foreign exchange rate Volatility, tender offer Volatility For Shares Measurement Input, Tender Offer [Member] Volatility For Shares Measurement Input, Tender Offer AGA-2025-5 AGA-2025-5 [Member] AGA-2025-5 ABX464-107 ABX464-107 [Member] ABX464-107 Number of shares issued at beginning of period (in shares) Number of shares issued at end of period (in shares) Number of shares issued (in shares) Number of shares issued Number of convertible notes converted Number Of Convertible Notes Converted Number Of Convertible Notes Converted Non cash changes: additional leases Increase through new leases, liabilities arising from financing activities Segment information Disclosure of entity's operating segments [text block] Total operating income Revenue and other operating income Kreos & Claret bond loans Kreos 1 & 2 Bond Loans [Member] Kreos 1 & 2 Bond Loans Range [domain] Range [domain] Capital commitments Capital commitments AGA-2025-2 AGA-2025-2 [Member] AGA-2025-2 Tranches [Domain] Tranches [Domain] Tranches [Domain] Trade and other current payables [abstract] DEPRECIATION Accumulated depreciation and amortisation [member] Disclosure Of Financial Gain (Loss) [Table] Disclosure Of Financial Gain (Loss) [Table] Disclosure Of Financial Gain (Loss) [Table] Financial gain (loss) Disclosure of finance income (cost) [text block] Increase (decrease) in financial liabilities at fair value due to reasonably possible decrease in unobservable input Increase (decrease) in fair value measurement due to reasonably possible decrease in unobservable input, liabilities Interest income Interest income Disclosure of composition of cash and cash equivalents Disclosure Of Composition Of Cash And Cash Equivalents [Table Text Block] Disclosure Of Composition Of Cash And Cash Equivalents Conversion of Kreos OCABSA and heights notes Increase (decrease) through conversion of convertible instruments, equity FROM 1 TO 2 YEARS Later than one year and not later than two years [member] Recurring fair value measurement Recurring fair value measurement [member] EXPECTED MATURITY Expected Maturity, Other Equity Instruments Granted Expected Maturity, Other Equity Instruments Granted Expiry scenario period, other equity instruments granted Expiry Scenario Period, Other Equity Instruments Granted Expiry Scenario Period, Other Equity Instruments Granted Non-current financial liabilities Non-current financial liabilities Total Expense from share-based payment transactions Exercise of Kreos/Claret and other share warrants Increase (decrease) through exercise of warrants, equity Total fair value of MRI, final redemption Final Redemption, Fair Value Of MRI, Measurement Input [Member] Final Redemption, Fair Value Of MRI , Measurement Input AGA-2025-3 AGA-2025-3 [Member] AGA-2025-3 Categories of financial assets [domain] Categories of financial assets [domain] Tranche 1 Tranche One [Member] Tranche One Carrying amount [member] Carrying amount [member] Percentage of reasonably possible increase in unobservable input, assets Percentage of reasonably possible increase in unobservable input, assets Financial Income (Loss) [Abstract] Financial Income (Loss) Notional amount Original principal amount Notional amount Unobservable inputs [domain] Unobservable inputs [domain] Changes in equity [abstract] Changes in equity [abstract] At-The-Market (ATM) Program At-The-Market (ATM) Program [Member] At-The-Market (ATM) Program 50 Mg 50 Mg [Member] 50 Mg Financial Risk Management [Abstract] Financial Risk Management [Abstract] Borrowings Other current borrowings and current portion of other non-current borrowings Disclosure of main data and assumptions used for the measurement of other equity instruments Disclosure of indirect measurement of fair value of goods or services received, other equity instruments granted during period [text block] Currency [Axis] Currency [Axis] Net proceeds from sale of treasury shares Proceeds from sale or issue of treasury shares Diluted loss per share (in euro per share) Diluted earnings (loss) per share Maturity [domain] Maturity [domain] Retirement benefit obligations Non-current provisions for employee benefits Right-of-use assets Right-of-use assets Categories of financial liabilities [axis] Categories of financial liabilities [axis] Vesting percentage Vesting Requirements For Share-Based Payment Arrangement, Vesting Percentage Vesting Requirements For Share-Based Payment Arrangement, Vesting Percentage Current prepaid expenses related to CRO Current Prepaid Expenses Related To CRO Current Prepaid Expenses Related To CRO Disclosure of terms and conditions of share-based payment arrangement [table] Disclosure of terms and conditions of share-based payment arrangement [table] Kreos & Claret Financing, Tranche A,B and C Kreos & Claret Financing, Tranche A,B and C [Member] Kreos & Claret Financing, Tranche A,B and C Disclosure of reconciliation of liabilities arising from financing activities [table] Disclosure of reconciliation of liabilities arising from financing activities [table] 2025, Tax Year 2025, Tax Year [Member] 2025, Tax Year At fair value At fair value [member] Repayments of conditional advances Repayments Of Conditional Advances Repayments Of Conditional Advances Total fair value of MRI, tender offer Tender Offer, Fair Value Of MRI, Measurement Input [Member] Tender Offer, Fair Value Of MRI , Measurement Input Increase / (decrease) in other liabilities / (assets) at fair value through profit and loss Losses On Financial Liabilities At Fair Value Through Profit Or Loss Losses On Financial Liabilities At Fair Value Through Profit Or Loss Royalty certificate, expiration period Royalty Certificate, Expiration Period Royalty Certificate, Expiration Period Schedule of earnings per share Earnings per share [text block] Disclosure Of Warrants Arrangements [Line Items] Disclosure Of Warrants Arrangements [Line Items] Disclosure Of Warrants Arrangements Intangible assets other than goodwill [abstract] Counterparty Name [Axis] Counterparty Name [Axis] Option pricing model Option pricing model [member] Disclosure of detailed information about property, plant and equipment [table] Disclosure of detailed information about property, plant and equipment [table] Acquisitions of intangible assets Purchase of intangible assets, classified as investing activities Number of warrants granted (in shares) Number Of Warrants Granted Number Of Warrants Granted AGA-2025-4 AGA-2025-4 [Member] AGA-2025-4