Stock-based compensation (Tables)
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12 Months Ended |
Dec. 31, 2023 |
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| Share-Based Payment Arrangement [Abstract] |
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| Schedule of Stock Option Activity |
A summary of stock option activity is as follows: | | | | | | | | | | | | | | | | | | | | | | | | | Number of Shares | | Weighted- Average Exercise Price | | Weighted Average Remaining Contractual Term | | Aggregate Intrinsic Value | | Outstanding at January 1, 2023 | 10,051,283 | | | $ | 9.84 | | | 7.2 | | $ | 8,197 | | | Granted | 4,017,763 | | | $ | 4.76 | | | | | | | Exercised | (102,596) | | | $ | 4.25 | | | | | | | Cancelled/forfeited | (3,063,605) | | | $ | 12.00 | | | | | | | Outstanding at December 31, 2023 | 10,902,845 | | | $ | 7.42 | | | 6.8 | | $ | 1,786 | | | | | | | | | | | Exercisable at December 31, 2023 | 6,499,540 | | | $ | 8.23 | | | 5.5 | | $ | 711 | |
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| Schedule of Restricted Stock Unit Activity |
A summary of the RSU activity is as follows: | | | | | | | | | | | | | | | | | | | | | | | | | Number
of Shares | | Weighted-Average
Remaining
Contractual Term | | Aggregate
Intrinsic Value | | Weighted-Average
Grant Date
Fair Value | | Unvested at January 1, 2023 | 1,870,791 | | | 1.5 | | $ | 10,963 | | | $ | 8.55 | | | Granted | 4,025,544 | | | — | | | | | $ | 4.42 | | | Vested | (572,825) | | | — | | | | | $ | 8.83 | | | Forfeited | (1,489,402) | | | — | | | | | $ | 6.25 | | | Unvested at December 31, 2023 | 3,834,108 | | | 1.4 | | $ | 8,895 | | | $ | 5.01 | |
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| Schedule of Stock-Based Compensation Expense by Award Type |
The following table presents stock-based compensation expense by award type included within the Company’s consolidated statements of operations and comprehensive loss: | | | | | | | | | | | | | | | | | | | Year ended December 31, | | (in thousands) | 2023 | | 2022 | | 2021 | Stock options | $ | 14,171 | | | $ | 15,814 | | | $ | 14,528 | | Restricted stock units and other stock awards | 6,184 | | | 5,175 | | | 3,522 | | | Employee stock purchase plan | 781 | | | 533 | | | 359 | | | Stock-based compensation expense included in total operating expenses | $ | 21,136 | | | $ | 21,522 | | | $ | 18,409 | |
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| Schedule of Stock-Based Compensation Expense as Reflected in the Company’s Condensed Consolidated Statements of Operations and Comprehensive Loss |
The following table presents stock-based compensation expense as reflected in the Company’s consolidated statements of operations and comprehensive loss: | | | | | | | | | | | | | | | | | | | Year ended December 31, | | (in thousands) | 2023 | | 2022 | | 2021 | | Research and development | $ | 11,043 | | | $ | 11,386 | | | $ | 9,984 | | | General and administrative | 10,093 | | | 10,136 | | | 8,425 | | | Stock-based compensation expense included in total operating expenses | $ | 21,136 | | | $ | 21,522 | | | $ | 18,409 | |
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| Schedule of Weighted Average Assumptions for Estimating Fair Value of Option Awards |
The fair value of each option award is estimated on the date of grant using the Black–Scholes option pricing model with the following weighted average assumptions: | | | | | | | | | | | | | | | | | | | December 31, | | 2023 | | 2022 | | 2021 | Risk-free interest rate | 3.8 | % | | 2.1 | % | | 0.9 | % | Expected dividend yield | — | % | | — | % | | — | % | Expected term (years) | 6.05 | | 5.99 | | 6.06 | Expected stock price volatility | 103 | % | | 88 | % | | 82 | % |
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