Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Weighted-Average Assumptions Used Principally in Determining Fair Value of Options Granted

The weighted-average assumptions used principally in determining the fair value of options granted were as follows:

	Three Months Ended March 31,
	2021			2020
Fair value of common stock	$	22.51		$	2.18
Expected term (in years)		6.0			5.9
Expected volatility		79.7	%		75.9	%
Risk-free interest rate		0.7	%		0.7	%
Dividend yield		—			—

Summary of Stock Option Activity

The following table summarizes the Company’s stock option activity for three months ended March 31, 2021:

	Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2021		5,084,679		$	3.79		9.42	$	32,086
Granted		394,934		$	22.51
Exercised		(38,216	)	$	1.31
Outstanding at March 31, 2021		5,441,397		$	5.16		9.24	$	206,544
Exercisable at March 31, 2021		989,860		$	1.80		8.85	$	40,772

Summary of Stock-Based Compensation Expense

Stock-based compensation expense was allocated as follows:

	Three Months Ended March 31,
(in thousands)	2021		2020
Research and development	$	449	$	47
General and administrative		442		65
Total stock-based compensation expense	$	891	$	112