Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 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 June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	1,888	$	825	$	3,574	$	2,413
General and administrative		2,447		1,834		5,111		3,289
Total stock-based compensation	$	4,335	$	2,659	$	8,685	$	5,702

Summary of Stock Option Activity

Stock Options

A summary of stock option activity for six months ended June 30, 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		1,992,500		$	14.18
Options exercised		(27,953	)	$	9.95
Options forfeited or cancelled		(92,020	)	$	12.68
Outstanding, June 30, 2022		5,747,844		$	14.16		8.74	$	7,050
Options exercisable, June 30, 2022		1,714,774		$	13.99		8.34	$	2,627
Vested and expected to vest, June 30, 2022		5,747,844		$	14.16		8.74	$	7,050

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,
	2022	2021	2022	2021
Fair value of common stock	$11.49 - $14.74	$10.29 - $15.93	$11.49 - $19.97	$10.29 - $16.82
Expected term (years)	5.5 - 6.1	0.9 - 6.1	5.5 - 6.1	0.9 - 6.1
Volatility	77.4% - 79.8%	77.9% - 78.6%	77.4% - 79.8%	77.9% - 79.8%
Risk free rates	2.8% - 3.0%	0.1% - 1.1%	1.6% - 3.0%	0.1% - 1.1%
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, 2022 is set forth below:

	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		(10,500	)	$	7.12
Outstanding, June 30, 2022		537,160		$	7.76