Stock-Based Compensation (Tables)

9 Months Ended

Sep. 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 September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Research and development	$	2,545	$	1,745	$	7,132	$	5,319
General and administrative		3,015		2,446		8,216		7,557
Total stock-based compensation	$	5,560	$	4,191	$	15,348	$	12,876

Summary of Stock Option Activity

Stock Options

A summary of stock option activity for the nine months ended September 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		4,167,242		$	5.48
Options exercised		(946	)	$	4.76
Options forfeited or cancelled		(619,818	)	$	12.35
Outstanding, September 30, 2023		9,749,498		$	10.74		8.4	$	—
Options exercisable, September 30, 2023		3,602,027		$	13.87		7.6	$	—
Vested and expected to vest, September 30, 2023		9,749,498		$	10.74		8.4	$	—

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 September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Fair value of common stock	$1.37 - $3.38	$14.16 - $16.89	$1.37 - $9.15	$11.49 - $19.97
Expected term (years)	5.5 - 6.1	6.0 - 6.1	5.5 - 6.1	5.5 - 6.1
Volatility	84.7% - 87.3%	79.5% - 80.7%	83.3% - 87.3%	77.4% - 80.7%
Risk free rates	4.1% - 4.6%	2.7% - 4.0%	3.5% - 4.6%	1.6% - 4.0%
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 nine months ended September 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		(69,955	)	$	7.6
RSUs forfeited		(54,525	)	$	7.2
Outstanding, September 30, 2023		586,800		$	7.8