Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of Stock-based Compensation Expense by Classification

Stock-based compensation expense by classification included within the Condensed Consolidated Statements of Operations and Comprehensive Loss was as follows (in thousands):

	Three Months Ended March 31,
	2023		2022
Research and development	$	4,612	$	3,764
General and administrative	9,270		18,264
Total stock-based compensation expense	$	13,882	$	22,028

Schedule of RSU Activity

A summary of the Company’s RSU activity was as follows:

	Restricted Stock Units Outstanding	Weighted-Average Value at Grant Date Per Share
Unvested RSUs as of December 31, 2022	872,077	$	5.98
RSUs granted	1,877,177	$	2.13
RSUs vested	(65,510)	$	5.98
RSUs forfeited or canceled	(70,537)	$	5.18
Unvested RSUs as of March 31, 2023	2,613,207	$	3.24

Schedule of Stock Option Activity

A summary of the Company’s stock option activity was as follows:

	Number of Stock Options	Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life (in years)	Aggregate Intrinsic Value (in thousands)
Options outstanding as of December 31, 2022	53,849,045	$	5.09	7.84	$	24,887
Granted	7,713,313	$	2.15
Exercised	0	$	—
Canceled or forfeited	(810,212)	$	6.58
Options outstanding as of March 31, 2023	60,752,146	$	4.70	7.91	$	17,475
Options exercisable as of March 31, 2023	29,726,200	$	4.53	6.67	$	15,734

Schedule of Assumptions Used in Black-Scholes Option-Pricing Model for Estimating Fair Value of Stock Options Granted

The fair value of stock options granted to employees, directors and consultants was estimated on the date of grant using the Black-Scholes option pricing model using the following weighted-average assumptions:

	Three Months Ended March 31,
	2023		2022
Risk-free interest rate	4.13	%	2.14	%
Expected volatility	91.9	%	85.2	%
Expected term (in years)	6.02		6.00
Expected dividend yield	0	%	0	%