Stockholders' Equity (Deficit) (Tables)

6 Months Ended

Jun. 30, 2024

Share-Based Payment Arrangement [Abstract]

Summary of RSU Activity

The following is a summary of RSU activity under our 2014 EIP and Inducement Plan:

	RSUs
	Shares			Weighted Average Grant Date Fair Value
Balance as of December 31, 2023		250,709		$	158.00
Granted		494,590		$	14.32
Forfeited		(45,968	)	$	100.74
Vested		(144,393	)	$	97.61
Balance as of June 30, 2024		554,938		$	50.40

Summary of Stock Option Activity

The following is a summary of stock option activity under our 2014 EIP and Inducement Plan:

	Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in thousands)
Balance as of December 31, 2023		428,786		$	290.75		6.5	$	—
Granted		16,500			11.00		—		—
Exercised		—			—		—		—
Forfeited or expired		(121,311	)		357.74		—		—
Balance as of June 30, 2024		323,975		$	251.42		7.0	$	—

Schedule of Common Stock Reserved for Future Issuance Under Equity Incentive Plans

The following shares of common stock were reserved for future issuance under our equity incentive plans as of June 30, 2024:

	Total Shares Reserved
2014 Equity Incentive Plan		819,558
2018 Inducement Plan		174,694
2024 Equity Incentive Plan		294,882
2014 Employee Stock Purchase Plan		40,190
Total reserved shares of common stock		1,329,324

Schedule of Stock-based Compensation, Related to Employee and Nonemployee Stock Awards

Stock-based Compensation Expense

The following is a summary of stock-based compensation expense for the periods presented:

	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
	(in thousands)				(in thousands)
Research and development	$	3,314	$	7,195	$	8,027	$	13,965
General and administrative		3,022		5,357		6,706		10,351
Total stock-based compensation expense	$	6,336	$	12,552	$	14,733	$	24,316