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Equity Incentive Plans and Stock-Based Compensation (Tables) | 6 Months Ended
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Jun. 30, 2024
Share-Based Payment Arrangement [Abstract] |
Schedule of Black-Scholes Option Pricing Model to Estimate Stock-based Compensation Expense for Stock Option Awards | The Company used Black-Scholes option pricing model to estimate stock-based compensation expense for stock option awards with the following assumptions:
| Three Months Ended June 30, |  | Six Months Ended June 30,
| 2024 |  | 2023 |  | 2024 |  | 2023
Expected volatility | 85.58% - 86.46% |  | 81.16% - 81.66% |  | 85.28% - 86.46% |  | 80.97% - 81.66%
Risk-free interest rate | 4.17% - 4.60% |  | 3.44% - 3.88% |  | 4.04% - 4.60% |  | 3.42% - 4.18%
Expected dividend | — |  | — |  | — |  | —
Expected term (in years) | 5.31 - 6.08 |  | 5.31 - 6.07 |  | 5.31 - 6.08 |  | 5.31 - 6.08
Underlying common stock fair value | $11.51 - $15.36 |  | $22.33 - $26.50 |  | $11.51 - $17.44 |  | $21.94 - $34.65
Schedule of Option Activity Under the 2015 Plan and 2020 Plan | A summary of option activity under the 2015 Plan and the 2020 Plan is as follows:
| Number of Options |  | Weighted- Average Exercise Price per Share |  | Weighted- Average Remaining Contractual Term (in Years) |  | Aggregate Intrinsic Value
Outstanding as of December 31, 2023 | 6,953,487 |  |  | $ | 17.95 |  |  | 7.70 |  | $ | 32,646 |
Granted | 2,134,869 |  |  | $ | 15.50 |  |  |  |  |
Exercised | (225,175) |  |  | $ | 7.25 |  |  |  |  |
Forfeited | (632,944) |  |  | $ | 17.56 |  |  |  |  |
Outstanding as of June 30, 2024 | 8,230,237 |  |  | $ | 17.64 |  |  | 7.93 |  | $ | 7,794 |
Exercisable as of June 30, 2024 | 3,973,720 |  |  | $ | 16.65 |  |  | 6.82 |  | $ | 7,306 |
Vested and expected to vest as of June 30, 2024 | 8,230,237 |  |  | $ | 17.64 |  |  | 7.93 |  | $ | 7,794 |
Schedule of Restricted Stock Activity | The following table sets forth the outstanding RSUs and related activity for the three and six months ended June 30, 2024.
| Restricted Stock Units |  | Weighted Average Grant Date Fair Value
Unvested and outstanding as of December 31, 2023 | 874,748 |  |  | $ | 29.85 |
Granted | 594,336 |  |  | $ | 17.44 |
Released | (210,085) |  |  | $ | 34.65 |
Forfeited | (78,253) |  |  | $ | 26.37 |
Unvested and outstanding as of June 30, 2024 | 1,180,746 |  |  | $ | 22.98 |
Schedule of Share-Based Payment Award, Equity Instruments Other Than Options, Valuation Assumptions | The fair value of the TSR PSUs were derived from a Monte Carlo simulation model that used the following key assumptions:
Valuation date share price |  | $ | 17.57 |
Award term (years) |  | 1.92
Volatility |  | 70.62 | %
Correlation coefficient |  | 0.3508
Average peer group volatility |  | 79.69 | %
Average peer group correlation coefficient |  | 0.4397
Risk-free interest rate |  | 2.84 | %
Schedule of Black-Scholes Option Pricing Model to Estimate Stock-based Compensation Expense for 2020 Employee Stock Purchase Plan | The Company used Black-Scholes option pricing model to estimate stock-based compensation expense for the 2020 ESPP with the following assumptions:
|  | Three and Six Months Ended June 30,
|  | 2024 |  | 2023
Risk-free interest rate |  | 5.27 | % |  | 5.20 | %
Expected term of options (in years) |  | 0.50 |  | 0.50
Expected stock price volatility |  | 63.92 | % |  | 69.15 | %
Expected dividends |  | — |  |  | — |
Schedule of Classification of Stock-based Compensation Expense | The following table presents the components and classification of stock-based compensation expense for the Company’s stock-based awards for the three and six months ended June 30, 2024 and 2023 (in thousands):
|  | Three Months Ended June 30, |  | Six Months Ended June 30,
|  | 2024 |  | 2023 |  | 2024 |  | 2023
Stock options and ESPP |  | $ | 6,287 |  |  | $ | 5,229 |  |  | $ | 12,645 |  |  | $ | 10,032 |
Restricted stock units |  | 3,314 |  |  | 2,963 |  |  | 6,560 |  |  | 5,569 |
Performance-based restricted stock units |  | 1,043 |  |  | 4,854 |  |  | 1,105 |  |  | 9,368 |
Total stock-based compensation expense |  | $ | 10,644 |  |  | $ | 13,046 |  |  | $ | 20,310 |  |  | $ | 24,969 |
Research and development expenses |  | $ | 4,102 |  |  | $ | 5,294 |  |  | $ | 7,172 |  |  | $ | 10,142 |
General and administrative expenses |  | $ | 6,542 |  |  | $ | 7,752 |  |  | $ | 13,138 |  |  | $ | 14,827 |

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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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