Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Stock-based Compensation Expense

Stock-based compensation expense was as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
(in thousands)	2022		2021		2022		2021
Research and development	$	3,890	$	4,010	$	11,122	$	11,274
General and administrative		6,965		6,276		21,151		16,841
Total stock-based compensation expense	$	10,855	$	10,286	$	32,273	$	28,115

Summary of Restricted Common Stock Activity

The following table summarizes restricted common stock activity for the nine months ended September 30, 2022:

	Shares			Weighted Average Grant Date Fair Value
Unvested at January 1, 2022		2,866,909		$	15.45
Granted		1,559,721			7.70
Forfeited		(136,888	)		20.67
Vested		(1,542,771	)		11.03
Unvested at September 30, 2022		2,746,971		$	13.27

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 (in years)		Aggregate Intrinsic Value
Options outstanding at January 1, 2022		6,155,055		$	23.42		8.80	$	480
Granted		2,974,481			7.49		—		—
Exercised		—			—		—		—
Forfeited		(630,027	)		23.34		—		—
Options outstanding at September 30, 2022		8,499,509		$	17.85		8.56	$	3,677
Options vested and exercisable at September 30, 2022		2,636,881		$	21.99		8.05	$	189

Schedule of Estimated Fair Value 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:

	Three Months Ended September 30, 2022			Nine Months Ended September 30, 2022
Expected term (in years)		6.11			6.07
Expected volatility		90.78	%		90.35	%
Risk-free interest rate		2.89	%		2.16	%
Expected dividend yield		—			—
Fair value of common stock	$	4.19		$	7.49