Stock-based compensation (Tables)
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6 Months Ended |
Jun. 30, 2025 |
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| Share-Based Payment Arrangement [Abstract] |
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| Schedule of stock-based compensation expense |
| | | | | | | | | | | | | | | Three Months Ended June 30, | | Six Months Ended June 30, | | | 2025 | | 2024 | | 2025 | | 2024 | Stock options | | $ | 1,316 | | $ | 1,138 | | $ | 2,539 | | $ | 1,587 | Restricted stock units | | | 282 | | | 311 | | | 531 | | | 621 | Total stock-based compensation expense | | $ | 1,598 | | $ | 1,449 | | $ | 3,070 | | $ | 2,208 | Included in: | | | | | | | | | | | | | General and administrative expense | | $ | 1,366 | | $ | 1,181 | | $ | 2,614 | | $ | 1,694 | Research and development expense | | | 232 | | | 268 | | | 456 | | | 514 | Total stock-based compensation expense | | $ | 1,598 | | $ | 1,449 | | $ | 3,070 | | $ | 2,208 |
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| Schedule of option activity transactions |
The following table summarizes stock option activity for the six months ended June 30, 2025 (in thousands, except share and per share data): | | | | | | | | | | | | | | | | | | Weighted- | | | | | | Number of | | | | | Average | | | | | | Shares | | Weighted- | | Remaining | | | | | | Underlying | | Average | | Contractual | | Aggregate | | | Outstanding | | Exercise | | Term | | Intrinsic | | | Options | | Price | | (in Years) | | Value (1) | Outstanding, January 1, 2025 | | 4,462,517 | | $ | 6.58 | | 7.4 | | $ | 619 | Granted | | 1,276,597 | | | 4.83 | | | | | | Exercised | | (99) | | | 4.71 | | | | | | Forfeited/expired | | (147) | | | 23.05 | | | | | | Outstanding, June 30, 2025 (2) | | 5,738,868 | | $ | 6.19 | | 7.5 | | $ | 10,766 | Vested and expected to vest, June 30, 2025 | | 5,738,868 | | $ | 6.19 | | 7.5 | | $ | 10,766 | Exercisable at June 30, 2025 | | 3,136,774 | | $ | 6.85 | | 6.3 | | $ | 4,042 |
| (1) | Aggregate intrinsic value represents the difference between the fair value of the Company’s Series A common stock on the last day of the fiscal period and the exercise price, multiplied by the number of options outstanding. |
| (2) | Includes 492,729 performance-based options with a weighted-average exercise price of $6.42, all of which were fully vested and exercisable. |
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| Schedule of restricted stock unit activity |
| | | | | | | | | | Weighted-Average | | | Restricted | | Grant Date | | | Stock Units | | Fair Value | Outstanding, January 1, 2025 | | 844,382 | | $ | 2.96 | Granted | | 254,017 | | | 4.71 | Outstanding, June 30, 2025 | | 1,098,399 | | $ | 3.36 |
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| Schedule of fair value assumptions |
| | | | | | | | | Six Months Ended June 30, | | | 2025 | | 2024 | Expected volatility | | 95 - 96 | % | | 92 - 96 | % | Risk-free interest rate | | 4.1 - 4.3 | % | | 4.1 - 4.5 | % | Dividend yield | | — | | | — | | Expected term (in years) | | 5.3 - 6.0 | | | 5.3 - 6.1 | |
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