Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

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 March 31,
	2022		2021
Research and development	$	1,687	$	1,588
General and administrative		2,663		1,455
Total stock-based compensation	$	4,350	$	3,043

Summary of Stock Option Activity

A summary of stock option activity for three months ended March 31, 2022 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, 2021		3,875,317		$	14.08		8.85	$	13,212
Options authorized		—
Options granted		1,555,000		$	14.59
Options exercised		(10,099	)	$	9.29
Options forfeited or cancelled		(44,073	)	$	14.21
Outstanding, March 31, 2022		5,376,145		$	14.24		8.89	$	30,825
Options exercisable, March 31, 2022		1,296,481		$	13.67		8.45	$	8,174
Vested and expected to vest, March 31, 2022		5,376,145		$	14.24		8.89	$	30,825

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 March 31,
	2022	2021
Fair value of common stock	$11.93 - $19.97	$8.33 - $11.39
Expected term (years)	5.8 - 6.1	5.9 - 6.1
Volatility	77.4% - 77.7%	79.2% - 79.8%
Risk free rates	1.6% - 2.4%	0.7% - 0.9%
Dividend rate	0.0%	0.0%

Summary of Restricted Stock Unit Activity

The summary of RSU activity and related information follows:

	Number of Units Outstanding			Weighted- Average Grant Date Fair Value
Outstanding, December 31, 2021		771,660		$	7.84
RSUs granted		—			-
RSUs Vested		(224,000	)	$	8.02
RSUs forfeited		(9,000	)	$	7.12
Outstanding, March 31, 2022		538,660		$	7.75