Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Stock-Based Compensation Expense

Total stock-based compensation expense recognized was as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Research and development	$	2,381	$	1,888	$	4,587	$	3,574
General and administrative		2,642		2,447		5,201		5,111
Total stock-based compensation	$	5,023	$	4,335	$	9,788	$	8,685

Summary of Stock Option Activity

Stock Options

A summary of stock option activity for the six months ended June 30, 2023 is set forth below:

	Number of Shares Underlying Outstanding Options			Weighted Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding, December 31, 2022		6,203,020		$	14.44		8.4	$	780
Options granted		2,561,200		$	7.53
Options exercised		(946	)	$	4.76
Options forfeited or cancelled		(424,242	)	$	12.68
Outstanding, June 30, 2023		8,339,032		$	12.41		8.4	$	20
Options exercisable, June 30, 2023		3,181,499		$	13.92		7.7	$	20
Vested and expected to vest, June 30, 2023		8,339,032		$	12.41		8.4	$	20

Schedule of Assumptions to Estimate Fair Value of Stock Options Using Black-Scholes Option Pricing Model

The assumptions used in the Black Scholes Model to calculate stock-based compensation are as follows:

	Three Months Ended June 30,		Six Months Ended June 30,
	2023	2022	2023	2022
Fair value of common stock	$2.43 - $5.84	$11.49 - $14.74	$2.43 - $9.15	$11.49 - $19.97
Expected term (years)	5.5 - 6.1	5.5 - 6.1	5.5 - 6.1	5.5 - 6.1
Volatility	84.6% - 86.5%	77.4% - 79.8%	83.3% - 86.5%	77.4% - 79.8%
Risk free rates	3.5% - 4.1%	2.8% - 3.0%	3.5% - 4.2%	1.6% - 3.0%
Dividend rate	0.0%	0.0%	0.0%	0.0%

Summary of Restricted Stock Unit Activity

The summary of RSU activity and related information for the six months ended June 30, 2023 is set forth below:

	Number of Units Outstanding			Weighted Average Grant Date Fair Value
Outstanding, December 31, 2022		197,580		$	7.8
RSUs granted		513,700		$	7.6
RSUs vested		(3,205	)	$	17.2
RSUs forfeited		(38,225	)	$	7.4
Outstanding, June 30, 2023		669,850		$	7.6