Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of Stock-based Compensation Expense

Stock-based compensation expense was as follows:

	Three Months Ended March 31,
(in thousands)	2023		2022
Research and development	$	3,423	$	3,341
General and administrative		6,606		7,126
Total stock-based compensation expense	$	10,029	$	10,467

Summary of Restricted Common Stock Activity

The following table summarizes restricted common stock activity for the three months ended March 31, 2023:

	Shares			Weighted Average Grant Date Fair Value
Unvested at January 1, 2023		2,239,106		$	13.75
Granted		1,806,519			6.63
Forfeited		(35,162	)		14.48
Vested		(334,747	)		11.93
Unvested at March 31, 2023		3,675,716		$	10.41

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, 2023		7,922,797		$	17.81		8.30	$	786
Granted		3,358,317			6.63		—		—
Exercised		—			—		—		—
Forfeited		(527,772	)		19.61		—		—
Options outstanding at March 31, 2023		10,753,342		$	14.23		8.66	$	46
Options vested and exercisable at March 31, 2023		3,231,896		$	20.57		7.76	$	42

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:

	Three Months Ended March 31, 2023			Three Months Ended March 31, 2022
Expected term (in years)		6.11			6.11
Expected volatility		94.50	%		90.53	%
Risk-free interest rate		3.46	%		1.73	%
Expected dividend yield		—			—
Fair value of common stock	$	6.63		$	9.19