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Equity Incentive Plans and Stock-Based Compensation (Tables)
 9 Months Ended
Sep. 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 September 30,Nine Months Ended September 30,
 2024202320242023
Expected volatility
85.14% - 85.74%
82.66% - 83.22%
85.14% - 86.46%
80.97% - 83.22%
Risk-free interest rate
3.45% - 4.20%
3.95% - 4.38%
3.45% - 4.60%
3.42% - 4.38%
Expected dividend————
Expected term (in years)
6.01 - 6.07
6.00 - 6.08
5.31 - 6.08
5.31 - 6.08
Underlying common stock fair value
$11.09 - $13.23
$16.01 - $18.80
$11.09 - $17.44
$16.01 - $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, 20236,953,487 $17.95 7.70$32,646 
Granted2,367,019 $15.12 
Exercised(237,008)$7.21 
Forfeited(828,177)$18.60 
Outstanding as of September 30, 20248,255,321 $17.38 7.68$8,356 
Exercisable as of September 30, 20244,328,248 $16.93 6.63$7,901 
Vested and expected to vest as of September 30, 20248,255,321 $17.38 7.68$8,356 
Schedule of Restricted Stock Activity The following table sets forth the outstanding RSUs and related activity for the nine months ended September 30, 2024.
Restricted Stock UnitsWeighted Average Grant Date Fair Value
Unvested and outstanding as of December 31, 2023874,748 $29.85 
Granted599,011 $17.39 
Released(425,979)$25.93 
Forfeited(96,653)$24.99 
Unvested and outstanding as of September 30, 2024951,127 $24.25 
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
Volatility70.62 %
Correlation coefficient0.3508
Average peer group volatility79.69 %
Average peer group correlation coefficient0.4397
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 Nine Months Ended September 30,
 20242023
Risk-free interest rate
4.80% - 5.27%
5.20% - 5.47%
Expected term of options (in years)0.500.50
Expected stock price volatility
50.95% - 63.92%
54.78% - 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 nine months ended September 30, 2024 and 2023 (in thousands):
Three Months Ended September 30,Nine Months Ended September 30,
2024202320242023
Stock options and ESPP$6,021 $5,498 $18,666 $15,530 
Restricted stock units2,706 2,990 9,266 8,559 
Performance-based restricted stock units172 1,875 1,277 11,242 
Total stock-based compensation expense$8,899 $10,363 $29,209 $35,331 
Research and development expenses$3,599 $4,378 $10,771 $14,520 
General and administrative expenses$5,300 $5,985 $18,438 $20,811