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Stock-Based Compensation (Tables) | 12 Months Ended
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Dec. 31, 2024
Summary of Option Plans | Stock option activity under the 2019 Plan is set forth below for the year ended December 31, 2024:
|  |  |  |  | Weighted |  |  | Average |  |  |  |
|  |  |  |  | Average |  |  | Remaining |  |  | Aggregate |
|  | Number of |  |  | Exercise |  |  | Contractual |  |  | Intrinsic |
|  | Shares |  |  | Price Per |  |  | Term |  |  | Value |
|  | Outstanding |  |  | Share |  |  | (Years) |  |  | (in thousands) |
Balances at December 31, 2023 |  |  | 4,099,947 |  |  | $ | 21.00 |  |  |  | 7.6 |  |  | $ | 23,206 |
Stock options granted |  |  | 1,648,459 |  |  |  | 21.74 |  |  |  |  |  |  |
Stock options exercised |  |  | (14,374 | ) |  |  | 4.67 |  |  |  |  |  |  |
Stock options forfeited |  |  | (728,712 | ) |  |  | 23.36 |  |  |  |  |  |  |
Balances at December 31, 2024 |  |  | 5,005,320 |  |  | $ | 20.94 |  |  |  | 7.2 |  |  | $ | 1 |
Vested and expected to vest at December 31, 2024 |  |  | 5,005,320 |  |  |  | 20.94 |  |  |  | 7.2 |  |  | $ | 1 |
Exercisable at December 31, 2024 |  |  | 3,224,884 |  |  |  | 19.65 |  |  | 6.5 |  |  |  | — |
Summary of RSU Activity | Restricted Stock Units (“RSU”) activity under the 2019 Plan is set forth below for the year ended December 31, 2024:
|  |  |  |  | Weighted |
|  |  |  |  | Average |
|  | Number of |  |  | Grant Date |
|  | Shares |  |  | Fair Value |
|  | Outstanding |  |  | Per Share |
Balances at December 31, 2023 |  |  | 13,500 |  |  | $ | 44.66 |
RSUs granted |  |  | — |  |  |  | — |
RSUs vested and settled |  |  | (13,500 | ) |  |  | 44.66 |
RSUs forfeited |  |  | — |  |  |  | — |
Balances at December 31, 2024 |  |  | — |  |  | $ | — |
Summary of Assumptions Used to Value Under Stock Option Plans | The fair value of the rights granted to employees under the 2019 ESPP was estimated using a Black-Scholes option-pricing model with the following valuation assumptions:
|  | For the Year Ended December 31,
|  | 2024 |  | 2023
Fair value |  | $0.91 - $5.90 |  | $4.79 - $12.12
Expected term (in years) |  | 0.50 - 2.00 |  | 0.50 - 2.00
Volatility |  | 95.6% - 165.3% |  | 64.3% - 93.2%
Risk-free interest rate |  | 4.21% - 5.53% |  | 4.14% - 5.51%
Dividend yield |  | — |  | —
Summary of Stock-based Compensation Expense | Total stock-based compensation expense recognized for stock options and RSUs granted to both employees and non-employees and for the employee stock purchase plan was as follows (in thousands):
|  | For the Year Ended December 31, |
|  | 2024 |  |  | 2023 |
Research and development |  | $ | 9,203 |  |  | $ | 7,941 |
General and administrative |  |  | 10,732 |  |  |  | 9,150 |
Total stock-based compensation expense |  | $ | 19,935 |  |  | $ | 17,091 |
Employee and Non-employees |
Summary of Assumptions Used to Value Under Stock Option Plans | The assumptions used to value employee and non-employee stock option awards granted under the Option Plans during the years ended December 31, 2024 and 2023, using the Black-Scholes option pricing model, were as follows:
|  | For the Year Ended December 31,
|  | 2024 |  | 2023
Fair value |  | $1.16 - $24.75 |  | $11.25 - $23.70
Expected term (in years) |  | 5.88 - 6.06 |  | 5.87 - 6.06
Volatility |  | 99.6% - 110.7% |  | 94.9% - 97.8%
Risk-free interest rate |  | 3.93% - 4.64% |  | 3.46% - 4.71%
Dividend yield |  | — |  | —

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- Definition Tabular disclosure of the number and weighted-average grant date fair value for restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock units that were granted, vested, or forfeited during the year. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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- Definition Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -SubTopic 10 -Topic 718 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (e) -SubTopic 10 -Topic 718 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 718 -SubTopic 10 -Subparagraph (f)(2) -Name Accounting Standards Codification -Paragraph 2 -Section 50 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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