Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2023

Summary of Assumptions Used in Black-Scholes Option Pricing Model

	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2023	2022	2023	2022
Risk-free interest rate	4.20%	2.65% - 4.09%	3.38% - 4.22%	1.70% - 4.09%
Expected volatility	80.8%	77.7% - 78.2%	76.3% - 81.3%	77.7% - 81.9%
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 Compensation Expense Relating to Stock Options

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
Research and development	$	1,387	$	1,719	$	4,314	$	5,380
General and administrative		1,447		1,149		4,122		5,137
Total stock option expense	$	2,834	$	2,868	$	8,436	$	10,517

Summary of Stock Option Activity

		Weighted
	Number of	Average Exercise
	Shares	Price
Outstanding, December 31, 2022	7,689,449	$	14.35
Granted	1,954,668		8.31
Exercised	(93,218)		6.00
Forfeited	(177,085)		11.19
Expired	(1,332,923)		14.48
Outstanding, September 30, 2023	8,040,891	$	13.03
Options exercisable, September 30, 2023	4,583,227

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, 2022	372,513	$	13.20
Awarded	601,172		7.81
Vested and released	(194,389)		12.26
Forfeited	(3,585)		10.46
Outstanding, September 30, 2023	775,711	$	9.27
Restricted stock units exercisable (vested and deferred), September 30, 2023	—