Stock-Based Compensation (Tables)
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6 Months Ended |
Jun. 30, 2026 |
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| Share-Based Payment Arrangement [Abstract] |
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| Stock-Based Compensation Expense |
The following stock-based compensation expense was recognized for the periods indicated (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended June 30, | | Six Months Ended June 30, | | 2026 | | 2025 | | 2026 | | 2025 | | Research and development | $ | 753 | | | $ | 2,237 | | | $ | 2,170 | | | $ | 5,320 | | | General and administrative | 1,221 | | | 1,453 | | | 2,450 | | | 2,756 | | | Total stock-based compensation expense | $ | 1,974 | | | $ | 3,690 | | | $ | 4,620 | | | $ | 8,076 | |
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| Valuation Assumptions Using the Black-Scholes Option-Pricing Model |
The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model using the assumptions in the following table for options issued during the period indicated: | | | | | | | | | | | | | Six Months Ended June 30, | | 2026 | | 2025 | | Expected dividend yield | 0% | | 0% | | Expected volatility | 112.6% - 114.0% | | 110.7% - 115.6% | | Risk-free interest rate | 3.7% - 4.4% | | 3.9% - 4.5% | | Expected term | 6.22 years | | 6.11 years |
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| Schedule of Stock Options Roll Forward |
The following table summarizes stock option activity during the six months ended June 30, 2026: | | | | | | | | | | | | | | | | | | | | | | | | | Shares | | Weighted-
Average
Exercise Price | | Weighted-Average
Remaining
Contractual Term
(Years) | | Aggregate
Intrinsic
Value
(in thousands) | | Outstanding, December 31, 2025 | 14,106,148 | | | $ | 11.72 | | | | | $ | 125 | | | Granted | 2,975,160 | | | 1.91 | | | — | | | $ | — | | | Exercised | (23,032) | | | 2.92 | | | — | | | $ | 24 | | | Forfeited | (1,251,731) | | | 4.28 | | | — | | | $ | — | | | Expired | (1,046,363) | | | 15.69 | | | — | | | $ | — | | | Outstanding, June 30, 2026 | 14,760,182 | | | $ | 10.10 | | | 6.4 | | $ | 13,003 | | | As of June 30, 2026: | | | | | | | | | Exercisable | 10,006,891 | | | $ | 13.26 | | | 5.1 | | $ | 2,327 | | | Vested and expected to vest | 14,359,528 | | | $ | 10.28 | | | 6.3 | | $ | 12,146 | |
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| Schedule of RSU Activity |
The following table summarizes RSU activity during the six months ended June 30, 2026: | | | | | | | | | | | | | Shares | | Weighted-Average Grant Date Fair Value | | Outstanding, December 31, 2025 | 745,796 | | | $ | 8.84 | | | Granted | 696,260 | | | 2.00 | | | Vested | (393,754) | | | 8.62 | | | Forfeited | (212,292) | | | 5.41 | | | Outstanding, June 30, 2026 | 836,010 | | | $ | 4.12 | |
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| Stock Option Additional Information [Table] |
The following table summarizes additional information on stock options (in thousands, except per share amounts): | | | | | | | | | | | | | | | | | | | Six Months Ended June 30, | | | | | | 2026 | | 2025 | Weighted-average fair value per share of stock options granted | | | | | $ | 1.60 | | | $ | 2.03 | | Total intrinsic value of stock options exercised | | | | | $ | 24 | | | $ | — | | Total cash received for stock options exercised | | | | | $ | 67 | | | $ | — | | Total grant date fair value of stock options vested | | | | | $ | 4,285 | | | $ | 9,494 | |
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