Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Stock-Based Compensation Expense

The following table presents stock-based compensation expense as reflected in the Company's consolidated statements of operations (in thousands):

	Year Ended December 31,
	2023		2022
Research and development	$	9,143	$	7,225
General and administrative		11,116		9,901
Total stock-based compensation	$	20,259	$	17,126

The following table presents stock-based compensation expense by type of award (in thousands):

	Year Ended December 31,
	2023		2022
Stock options	$	18,060	$	14,054
Restricted stock units (including performance-based RSUs)		2,023		2,878
Employee Stock Purchase Plan		176		194
Total	$	20,259	$	17,126

Summary of Stock Option Activity

A summary of stock option activity for the year ended December 31, 2023 is set forth below (in thousands, except share and per share data):

	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		4,293,442		$	5.36
Options exercised		(946	)	$	4.76
Options forfeited or cancelled		(1,112,411	)	$	10.59
Outstanding, December 31, 2023		9,383,105		$	10.64		8.2	$	45
Options exercisable, December 31, 2023		3,984,821		$	13.65		7.4	$	6
Vested and expected to vest, December 31, 2023		9,383,105		$	10.64		8.2	$	45

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:

	Year Ended December 31,
	2023	2022
Fair value of common stock	$1.32 - $9.15	$8.94 - $19.97
Expected term (years)	5.5 - 6.1 years	5.5 - 6.1 years
Volatility	83.25% - 92.87%	77.4% - 81.7%
Risk free rates	3.5% - 4.86%	1.6% - 4.22%
Dividend rate	0.0%	0.0%

Summary of Restricted Stock Unit Activity

The summary of RSU activity and related information for the year ended December 31, 2023 is set forth below:

	Number of Units Outstanding			Weighted Average Grant Date Fair Value
Outstanding, December 31, 2022		197,580		$	7.80
RSUs granted		513,700		$	7.47
RSUs vested		(194,455	)	$	7.43
RSUs forfeited		(62,625	)	$	7.07
Outstanding, December 31, 2023		454,200		$	7.69