Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2024

Summary of Assumptions Used in Black-Scholes Option Pricing Model

	Three Months Ended		Six Months Ended
	June 30,		June 30,
	2024	2023	2024	2023
Risk-free interest rate	4.34%	3.38% - 3.89%	4.12% - 4.34%	3.38% - 4.22%
Expected volatility	89.8%	80.3% - 81.3%	89.6% - 89.8%	76.3% - 81.3%
Expected dividend yield	0%	0%	0%	0%
Expected life of employee and Board options (in years)	6.25	6.25	6.25	6.25

Summary of Stock Option Activity

		Weighted
	Number of	Average Exercise
	Shares	Price
Outstanding, December 31, 2023	7,897,647	$	12.99
Granted	3,045,125		0.86
Exercised	—		—
Forfeited	(3,139,154)		4.81
Expired	(1,735,737)		14.15
Outstanding, June 30, 2024	6,067,881	$	10.80
Options exercisable, June 30, 2024	3,797,495

Employees And Non-Employee Members Of Board Of Directors [Member]

Summary of Restricted Stock Unit Activity

		Weighted
	Number of	Average Grant
	Units	Date Fair Value
Outstanding, December 31, 2023	566,324	$	9.27
Awarded	903,883		0.66
Vested and released	(357,060)		7.58
Forfeited	(136,348)		10.57
Outstanding, June 30, 2024	976,799	$	1.74
Restricted stock units exercisable (vested and deferred), June 30, 2024	—

Employee Stock Option [Member]

Summary of Compensation Expense Recognized

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2024		2023		2024		2023
Research and development	$	275	$	1,447	$	779	$	2,927
General and administrative		1,145		1,434		2,374		2,675
Total stock option expense	$	1,420	$	2,881	$	3,153	$	5,602

Restricted Stock Units [Member]

Summary of Compensation Expense Recognized

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2024			2023		2024	2023
Research and development	$	(6)	$	116	$	249	$	295
General and administrative		327		445		1,684		898
Total restricted stock unit expense	$	321	$	561	$	1,933	$	1,193