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Stock-Based Compensation (Tables) | 9 Months Ended
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Sep. 30, 2023
Share-Based Payment Arrangement [Abstract] |
Summary of Stock-Based Compensation Expense | Total stock-based compensation expense recognized was as follows (in thousands):
|  | Three Months Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2023 |  |  | 2022 |  |  | 2023 |  |  | 2022 |
Research and development |  | $ | 2,545 |  |  | $ | 1,745 |  |  | $ | 7,132 |  |  | $ | 5,319 |
General and administrative |  |  | 3,015 |  |  |  | 2,446 |  |  |  | 8,216 |  |  |  | 7,557 |
Total stock-based compensation |  | $ | 5,560 |  |  | $ | 4,191 |  |  | $ | 15,348 |  |  | $ | 12,876 |
Summary of Stock Option Activity | Stock Options A summary of stock option activity for the nine months ended September 30, 2023 is set forth below:
|  | Number of Shares Underlying Outstanding Options |  |  | Weighted Average Exercise Price |  |  | Weighted- Average Remaining Contractual Term (in years) |  |  | Aggregate Intrinsic Value (in thousands) |
Outstanding, December 31, 2022 |  |  | 6,203,020 |  |  | $ | 14.44 |  |  |  | 8.4 |  |  | $ | 780 |
Options granted |  |  | 4,167,242 |  |  | $ | 5.48 |  |  |  |  |  |  |
Options exercised |  |  | (946 | ) |  | $ | 4.76 |  |  |  |  |  |  |
Options forfeited or cancelled |  |  | (619,818 | ) |  | $ | 12.35 |  |  |  |  |  |  |
Outstanding, September 30, 2023 |  |  | 9,749,498 |  |  | $ | 10.74 |  |  |  | 8.4 |  |  | $ | — |
Options exercisable, September 30, 2023 |  |  | 3,602,027 |  |  | $ | 13.87 |  |  |  | 7.6 |  |  | $ | — |
Vested and expected to vest, September 30, 2023 |  |  | 9,749,498 |  |  | $ | 10.74 |  |  |  | 8.4 |  |  | $ | — |
Schedule of Assumptions to Estimate Fair Value of Stock Options Using Black-Scholes Option Pricing Model | The assumptions used in the Black Scholes Model to calculate stock-based compensation are as follows:
|  | Three Months Ended September 30, |  | Nine Months Ended September 30,
|  | 2023 |  | 2022 |  | 2023 |  | 2022
Fair value of common stock |  | $1.37 - $3.38 |  | $14.16 - $16.89 |  | $1.37 - $9.15 |  | $11.49 - $19.97
Expected term (years) |  | 5.5 - 6.1 |  | 6.0 - 6.1 |  | 5.5 - 6.1 |  | 5.5 - 6.1
Volatility |  | 84.7% - 87.3% |  | 79.5% - 80.7% |  | 83.3% - 87.3% |  | 77.4% - 80.7%
Risk free rates |  | 4.1% - 4.6% |  | 2.7% - 4.0% |  | 3.5% - 4.6% |  | 1.6% - 4.0%
Dividend rate |  | 0.0% |  | 0.0% |  | 0.0% |  | 0.0%
Summary of Restricted Stock Unit Activity | The summary of RSU activity and related information for the nine months ended September 30, 2023 is set forth below:
|  | Number of Units Outstanding |  |  | Weighted Average Grant Date Fair Value |
Outstanding, December 31, 2022 |  |  | 197,580 |  |  | $ | 7.8 |
RSUs granted |  |  | 513,700 |  |  | $ | 7.6 |
RSUs vested |  |  | (69,955 | ) |  | $ | 7.6 |
RSUs forfeited |  |  | (54,525 | ) |  | $ | 7.2 |
Outstanding, September 30, 2023 |  |  | 586,800 |  |  | $ | 7.8 |

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