Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Restricted Common Stock Activity

The following table summarizes restricted common stock activity for the year ended December 31, 2020:

	Shares			Weighted Average Grant Date Fair Value
Unvested at January 1, 2020		4,403,148		$	1.87
Granted		315,023			21.07
Forfeited		(22,316	)		19.25
Vested		(1,284,876	)		1.84
Unvested at December 31, 2020		3,410,979		$	3.55

Summary of Stock Option Activity

The following table summarizes stock option activity (in thousands, except share and per share data):

	Shares			Weighted Average Exercise Price		Weighted Average Contractual Life		Aggregate Intrinsic Value
Options outstanding at January 1, 2020		44,960		$	3.01	9.5		$	—
Granted		3,952,949			18.08				—
Forfeited		(25,000	)		27.97				226
Exercised		—			—				—
Options outstanding at December 31, 2020		3,972,909		$	17.84		9.6	$	81,822
Options vested and exercisable at December 31, 2020		20,609		$	5.56		8.9	$	678

Schedule of Estimated Fair Value Weighted-Average Assumptions Using Black-Scholes Option-Pricing Model

The fair value was estimated on the date of grant using the Black-Scholes option-pricing model, with the following weighted-average assumptions:

	Year Ended December 31,
	2020			2019
Expected term (in years)		6.08			6.25
Expected volatility		95	%		84	%
Risk-free interest rate		0.36	%		1.65	%
Expected dividend yield		—			—
Fair value of common stock	$	18.08		$	3.01

Schedule of Stock-based Compensation Expense

Stock-based compensation expense was as follows:

	Years Ended December 31,
(in thousands)	2020		2019
Research and development	$	3,571	$	547
General and administrative		5,858		2,343
Total stock-based compensation expense	$	9,429	$	2,890