Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of Stock-Based Compensation Expense Recorded in Statements of Operations

The Company recorded stock-based compensation expense in the following expense categories in its accompanying statements of operations:

	Year Ended December 31,
(in thousands)	2023		2022
Research and development	$	12,626	$	11,549
General and administrative		12,990		13,595
	$	25,616	$	25,144

Summary of Stock Option Activity

The following table summarizes stock option activity for the Plan in the years indicated:

	Number of shares			Weighted average exercise price per share		Weighted average remaining contractual term (years)
Outstanding at January 1, 2022		7,179,482		$	15.36		8.66
Granted		3,884,429		$	7.58
Exercised		(217,905	)	$	1.78
Forfeited		(1,455,076	)	$	17.84
Outstanding at December 31, 2022		9,390,930		$	12.08		8.31
Granted		3,238,898		$	6.68
Exercised		(26,899	)	$	1.78
Forfeited		(704,483	)	$	12.58
Outstanding at December 31, 2023		11,898,446		$	10.60		7.77
Exercisable at December 31, 2023		6,084,483		$	11.62		6.96

Summary of Information about Stock Options Outstanding

The following table summarizes information about stock options outstanding and exercisable at December 31, 2023 under the Plan:

	Options Outstanding						Options Exercisable
Range of Exercise Prices	Number Outstanding		Weighted Average Remaining Contractual Life (in years)		Weighted Average Exercise Price		Number Exercisable		Weighted Average Exercise Price
$0.31 - $4.88		3,061,004		6.82	$	2.80		2,400,106	$	2.40
$4.89 - $7.50		3,905,574		8.99		6.57		366,158		5.83
$7.51 - $13.04		3,141,601		7.28		11.87		2,149,353		12.19
$13.05 - $88.98		1,790,267		7.56		30.51		1,168,866		31.32
		11,898,446						6,084,483

Schedule of Fair Value of Each Option Estimated on Date of Grant Using Weighted Average Assumptions

The fair value of each option was estimated on the date of grant using the weighted average assumptions in the table below:

	Year Ended December 31,
	2023			2022
Expected volatility		83.57	%		84.67	%
Risk-free interest rate		3.82	%		2.73	%
Expected life (in years)		6.02			6.03
Expected dividend yield		—			—

Summary of Activity related to RSA Stock-Based Payment Awards

The following table summarizes activity related to RSA stock-based payment awards:

	Number of shares			Weighted- average grant date fair value
Unvested balance at January 1, 2022		611,608		$	2.29
Vested		(386,476	)	$	2.05
Forfeited		(23,416	)	$	1.89
Unvested balance at December 31, 2022		201,716		$	2.81
Vested		(174,708	)	$	2.74
Unvested balance at December 31, 2023		27,008		$	3.26

Summary of Activity related to RSU Stock-Based Payment Awards

The following table summarizes activity related to RSU stock-based payment awards:

	Number of shares			Weighted- average grant date fair value
Outstanding at January 1, 2022		20,000		$	18.32
Granted		150,000		$	4.86
Forfeited		(5,000	)	$	18.32
Outstanding at December 31, 2022		165,000		$	6.08
Vested		(61,250	)	$	5.96
Outstanding at December 31, 2023		103,750		$	6.16