Stock Incentive Plan (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Stock Option Activity

The following table summarizes stock option activity during the year ended December 31, 2023:

		Number of Options			Weighted-Average Exercise Price (per Share)		Weighted-Average Remaining Contract Term (in Years)		Aggregate Intrinsic Value (in Thousands)
Outstanding at December 31, 2022			9,637,022		$	5.35
Exercisable at December 31, 2022			4,066,881			4.17
	Granted		3,167,750			1.08
	Exercised		(23,479	)		0.56
	Canceled or forfeited		(1,029,544	)		5.56
Outstanding at December 31, 2023			11,751,749		$	4.19		8.0	$	93
Exercisable at December 31, 2023			6,045,163		$	4.55		7.3	$	52

Summary of Equity Based Compensation Expense

The classification of stock-based compensation expense is summarized as follows (in thousands):

	Year Ended December 31,
	2023		2022
Research and development	$	3,748	$	3,970
Selling, general and administrative		7,656		9,699
Total stock-based compensation expense	$	11,404	$	13,669

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

The following table shows the weighted-average assumptions used to compute the fair value of the awards granted to employees and nonemployees using the Black-Scholes option pricing model during the periods below:

	Year Ended December 31,
Assumption	2023	2022
Expected volatility	72.47%	57.56%
Expected term (years)	5.3−6.1	5.2−6.1
Expected dividend yield	0.00%	0.00%
Risk-free interest rate	4.15%	1.98%

Schedule of Common Stock Reserved for Future Issuance

Common stock reserved for future issuance under equity incentive plans consisted of the following as of December 31, 2023:

Stock options and restricted stock units issued and outstanding under all Plans	15,829,198
Authorized for future grants under the 2021 Plan	3,810,957
Authorized for future purchases under the ESPP	540,679
Total as of December 31, 2023	20,180,834

The table above does not include 34,384 of common stock for early exercised stock options that remain subject to the Company’s repurchase right.

Schedule of RSU activity during the year

Restricted stock units (“RSUs”) represent the right to receive common stock, subject to vesting for continued service to the Company. The following table summarizes RSU activity during the year ended December 31, 2023:

		Number of Units			Weighted-Average Grant Date Fair Value (per Unit)
Outstanding at December 31, 2022			-		$	-
	Granted		4,743,850			1.13
	Vested		(415,528	)		1.78
	Canceled		(250,873	)		1.88
Outstanding at December 31, 2023			4,077,449		$	1.02