Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Schedule of Stock Option Activity

Stock option activity in 2023 for employee and non-employee awards and related information is as follows (in thousands, except per share and contractual term data):

	Number of Outstanding Options	Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Balance at December 31, 2022	9,352	$	15.28
Granted	4,015	14.47
Exercised	(149)	3.81
Forfeited/expired	(723)	19.52
Balance at December 31, 2023	12,495	$	14.91	7.91	$	15,833
Vested and expected to vest at December 31, 2023	12,495	$	14.91	7.91	$	15,833
Exercisable at December 31, 2023	6,246	$	14.39	7.11	$	13,061

The following summarizes additional information regarding stock options (in thousands, except per share data):

	Year Ended December 31,
	2023		2022		2021
Cash received from options exercised	$	573	$	470	$	930
Intrinsic value of options exercised	$	2,421	$	6,724	$	3,436
Weighted-average grant date fair value per share	$	10.33	$	11.11	$	16.78

Schedule of Unvested Restricted Stock Units Roll Forward

The following table summarizes the RSU activity for the year ended December 31, 2023 (in thousands, except per share data):

	Number of Shares	Weighted-Average Grant Date Fair Value
Unvested at December 31, 2022	—	$	—
Granted	822	18.89
Vested	—	—
Forfeited	(64)	20.78
Unvested at December 31, 2023	758	$	18.73

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions

The assumptions used in the Black-Scholes model to determine the fair value of stock option grants and shares purchasable under the ESPP were as follows:

	Options			ESPP
	Year Ended December 31,			Year Ended December 31,
	2023	2022	2021	2023	2022	2021
Risk-free interest rate	3.5% - 4.9%	1.5% - 4.2%	0.5% - 1.3%	5.4%	2.2% - 4.7%	0.1%
Expected volatility	78% - 82%	85%	86% - 88%	68% - 76%	78% - 79%	69% - 75%
Expected term (in years)	5.5 - 6.1	5.5 - 6.1	5.5 - 6.1	0.5	0.5	0.5
Expected dividend yield	—%	—%	—%	—%	—%	—%

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions

The assumptions used in the Black-Scholes model to determine the fair value of stock option grants and shares purchasable under the ESPP were as follows:

	Options			ESPP
	Year Ended December 31,			Year Ended December 31,
	2023	2022	2021	2023	2022	2021
Risk-free interest rate	3.5% - 4.9%	1.5% - 4.2%	0.5% - 1.3%	5.4%	2.2% - 4.7%	0.1%
Expected volatility	78% - 82%	85%	86% - 88%	68% - 76%	78% - 79%	69% - 75%
Expected term (in years)	5.5 - 6.1	5.5 - 6.1	5.5 - 6.1	0.5	0.5	0.5
Expected dividend yield	—%	—%	—%	—%	—%	—%

Schedule of Allocated Stock-based Compensation Expense

The allocation of stock-based compensation expense was as follows (in thousands):

	Year Ended December 31,
	2023		2022		2021
Research and development expense	$	22,007	$	15,222	$	9,228
General and administrative expense	16,215		11,917		7,828
Total stock-based compensation expense	$	38,222	$	27,139	$	17,056