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Stock-Based Compensation (Tables)
 9 Months Ended
Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]  
Schedule of Total Employee, Director and Non-Employee Stock-Based Compensation Expense Recognized
Total employee, director and non-employee stock-based compensation expense recognized for the three and nine months ended September 30, 2024 and 2023 are as follows (in thousands):
Three Months Ended
September 30,		Nine Months Ended
September 30,
2024202320242023
General and administrative $5,158 $4,487 $18,326 $13,234 
Research and development 7,180 8,409 22,623 25,824 
$12,338 $12,896 $40,949 $39,058 
Three Months Ended
September 30,		Nine Months Ended
September 30,
2024202320242023
Stock options$6,760 $6,314 $24,578 $20,139 
ESPP206 307 623 970 
RSUs5,372 6,275 15,748 17,949 
$12,338 $12,896 $40,949 $39,058 
Summary of Stock Option Activity
The following table summarizes option activity under our stock plans and related information:
Number of
Shares Subject
to Outstanding
Options		Weighted
Average
Exercise
Price
(Per
Share)		Weighted
Average
Remaining
Contractual
Term
(in years)		Aggregate
Intrinsic
Value
(in thousands)
Balance at December 31, 202311,142,986$29.60 6.03$9,977 
Options granted2,297,551$22.21 
Options forfeited(614,922)$32.36 
Options exercised(222,149)$11.76 
Balance at September 30, 202412,603,466$28.44 5.96$6,942 
Exercisable8,522,788$29.56 4.62$6,550 
Schedule of Weighted Average Assumptions Used for Estimation of Fair Value of Stock Options We estimated the fair value of each equity award, including stock options and shares issued under our ESPP, using the Black-Scholes option-pricing model based on the date of grant of such stock option or ESPP share issuance date, with the following weighted average assumptions for the three and nine months ended September 30, 2024 and 2023:
OptionsOptions
Three Months Ended
September 30,		Nine Months Ended
September 30,
2024202320242023
Expected term (years)5.86.16.46.1
Expected volatility50.8 %50.0 %50.1 %50.5 %
Risk-free interest rate4.15 %4.43 %4.18 %4.18 %
Expected dividend yield— %— %— %— %
Schedule of Weighted Average Assumptions Used for Estimation of Fair Value of ESPP
ESPPESPP
Three Months Ended
September 30,		Nine Months Ended
September 30,
2024202320242023
Expected term (years)
0.5 - 2.0
0.5 - 2.0
0.5 - 2.0
0.5 -2.0
Expected volatility
43.0% - 44.6%
38.2% - 55.7%
43.0% - 44.6%
38.2% - 55.7%
Risk-free interest rate
4.71% - 5.40%
0.13% - 5.39%
4.71% - 5.40%
0.13% - 5.39%
Expected dividend yield— %— %— %— %
Summary of Restricted Stock Unit Activity
The following table summarizes the RSU activity for the nine-month period ended September 30, 2024:
Restricted
Stock
Units		Weighted
Average Grant
Date Fair Value
(Per unit)
Unvested RSUs at December 31, 20231,490,040$30.66 
Granted1,026,22022.31 
Vested(595,399)31.49 
Forfeited(167,097)28.89 
Unvested RSUs at September 30, 20241,753,764$25.57