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Stock-Based Compensation (Tables) | 6 Months Ended
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Jun. 30, 2024
Share-Based Payment Arrangement [Abstract] |
Summary of Stock Option Activity | The following table summarizes stock option activity under the Company’s equity incentive plans for the six months ended June 30, 2024:
|  |  |  |  |  |  |  | Weighted |  |  |  |
|  |  |  |  | Weighted |  |  | Average |  |  |  |
|  |  |  |  | Average |  |  | Remaining |  |  | Aggregate |
|  | Number of |  |  | Exercise |  |  | Contractual |  |  | Intrinsic |
|  | Options |  |  | Price |  |  | Term |  |  | Value |
|  |  |  |  |  |  |  | (In years) |  |  | (In thousands) |
Balance outstanding as of December 31, 2023 |  |  | 4,686,577 |  |  | $ | 14.11 |  |  |  | 7.9 |  |  | $ | 11,712 |
Granted |  |  | 2,530,900 |  |  |  | 9.96 |  |  |  |  |  |  |
Exercised |  |  | (27,981 | ) |  |  | 2.20 |  |  |  |  |  |  |
Forfeited |  |  | (144,545 | ) |  |  | 12.49 |  |  |  |  |  |  |
Balance outstanding as of June 30, 2024 |  |  | 7,044,951 |  |  | $ | 12.70 |  |  |  | 8.1 |  |  | $ | 6,409 |
Exercisable as of June 30, 2024 |  |  | 2,783,861 |  |  | $ | 14.89 |  |  |  | 6.6 |  |  | $ | 5,140 |
Summary of Estimated Fair Value of Stock Option Awards Granted Using Black-Scholes Option-Pricing Model | The fair value of stock option awards granted for the periods indicated was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions:
|  | Six Months Ended June 30,
|  | 2024 |  | 2023
Expected term (years) |  | 5.5–6.1 |  | 5.5–6.1
Expected volatility |  | 87.3–90.4% |  | 91.6–98.2%
Risk-free interest rate |  | 3.8–4.6% |  | 3.4–3.8%
Expected dividend |  | — |  | —
As of June 30, 2024, total unrecognized stock-based compensation expense related to unvested stock options was $32.5 million, which is expected to be recognized over a weighted-average period of 2.8 years. RSU and PSUs RSUs generally vest annually over a two or three-year period. PSUs generally contain performance conditions associated with corporate goals, such as achievement of certain development milestones, that vests upon achievement over a one to three-year period.
Summary of Restricted Stock Unit Activity | The following table summarizes RSU and PSU activity for the six months ended June 30, 2024:
|  | RSUs |  |  | PSUs |
|  | Number of Shares |  |  | Weighted-Average Grant Date Fair Value per Share |  |  | Number of Shares |  |  | Weighted-Average Grant Date Fair Value per Share |
Balance outstanding as of December 31, 2023 |  |  | 688,382 |  |  | $ | 10.72 |  |  |  | 299,168 |  |  | $ | 5.96 |
Granted |  |  | 656,950 |  |  |  | 9.96 |  |  |  | 192,000 |  |  |  | 9.98 |
Vested |  |  | (170,372 | ) |  |  | 13.76 |  |  |  | (159,168 | ) |  |  | 7.00 |
Forfeited |  |  | (44,837 | ) |  |  | 8.50 |  |  |  | (10,000 | ) |  |  | 9.98 |
Balance outstanding as of June 30, 2024 |  |  | 1,130,123 |  |  | $ | 9.91 |  |  |  | 322,000 |  |  | $ | 7.72 |
As of June 30, 2024, total unrecognized stock-based compensation expense related to RSUs and PSUs was $10.4 million, which is expected to be recognized over a weighted-average period of 1.7 years. Stock-Based Compensation
Summary of Stock-Based Compensation Expense | The Company recorded stock-based compensation expense for the periods indicated as follows (in thousands):
|  | Three Months Ended June 30, |  |  | Six Months Ended June 30, |
|  | 2024 |  |  | 2023 |  |  | 2024 |  |  | 2023 |
Research and development |  | $ | 2,342 |  |  | $ | 1,712 |  |  | $ | 4,657 |  |  | $ | 3,199 |
General and administrative |  |  | 2,827 |  |  |  | 2,425 |  |  |  | 5,510 |  |  |  | 4,489 |
Total stock-based compensation |  | $ | 5,169 |  |  | $ | 4,137 |  |  | $ | 10,167 |  |  | $ | 7,688 |

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