Stock-Based Compensation (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2024

Dec. 31, 2023

Summary of Assumptions Used in Black-Scholes Option Pricing Model

	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2024	2023	2024	2023
Risk-free interest rate	N/A	4.20%	4.12% - 4.34%	3.38% - 4.22%
Expected volatility	N/A	80.8%	89.6% - 89.8%	76.3% - 81.3%
Expected dividend yield	N/A	0%	0%	0%
Expected life of employee and Board options (in years)	N/A	6.25	6.25	6.25

	Year Ended December 31,
	2023		2022		2021
Risk-free interest rate	3.38% - 4.65	%	1.70% - 4.21	%	0.66% - 1.41	%
Expected volatility	76.3% - 81.3	%	77.7% - 81.9	%	71.6% - 83.5	%
Expected dividend yield	0	%	0	%	0	%
Expected life of employee and Board options (in years)	6.25		6.25		6.25

Summary of Compensation Expense Recognized

	Year Ended December 31,
	2023		2022		2021
Research and development	$	5,973	$	7,222	$	7,126
General and administrative		5,634		6,426		9,569
Total stock option expense	$	11,607	$	13,648	$	16,695

Summary of Stock Option Activity

		Weighted
	Number of	Average Exercise
	Shares	Price
Outstanding, December 31, 2023	658,138	$	155.88
Granted	253,760		10.32
Exercised	—		—
Forfeited	(275,941)		60.96
Expired	(280,993)		179.04
Outstanding, September 30, 2024	354,964	$	107.40
Options exercisable, September 30, 2024	190,407

		Weighted		Aggregate
	Number of	Average Exercise		Intrinsic
	Shares	Price		Value
Outstanding, December 31, 2022	640,787	$	172.20
Granted	167,056		97.80
Exercised	(7,768)		72.00
Forfeited	(23,836)		111.00
Expired	(118,101)		176.88
Outstanding, December 31, 2023	658,138	$	155.88	$	—
Weighted average remaining contractual life as of December 31, 2023 (in years)	6.71
Options exercisable, December 31, 2023	403,337	$	176.28	$	—
Weighted average remaining contractual life as of December 31, 2023 (in years)	5.46
Options vested and expected to vest as of December 31, 2023	658,138	$	155.88	$	—
Weighted average remaining contractual life as of December 31, 2023 (in years)	6.71

Employees And Non-Employee Members Of Board Of Directors

Summary of Restricted Stock Unit Activity

		Weighted
	Number of	Average Grant
	Units	Date Fair Value
Outstanding, December 31, 2023	47,194	$	111.24
Awarded	75,323		7.92
Vested and released	(30,494)		93.72
Forfeited	(11,362)		126.84
Outstanding, September 30, 2024	80,661	$	19.20
Restricted stock units exercisable (vested and deferred), September 30, 2024	—

		Weighted
	Number of	Average Grant
	Units	Date Fair Value
Outstanding, December 31, 2022	31,043	$	158.40
Awarded	50,098		93.72
Vested and released	(16,939)		149.52
Forfeited	(17,008)		107.52
Outstanding, December 31, 2023	47,194	$	111.24
Restricted stock units exercisable (vested and deferred), December 31, 2023	—

Stock Options

Summary of Compensation Expense Recognized

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2024		2023		2024		2023
Research and development	$	16	$	1,387	$	795	$	4,314
General and administrative		1,120		1,447		3,494		4,122
Total stock option expense	$	1,136	$	2,834	$	4,289	$	8,436

Restricted Stock Units

Summary of Compensation Expense Recognized

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2024		2023		2024		2023
Research and development	$	—	$	90	$	249	$	385
General and administrative		353		410		2,036		1,308
Total restricted stock unit expense	$	353	$	500	$	2,285	$	1,693