Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2024

Share-Based Payment Arrangement [Abstract]

Summary of Stock Option Activity

The following table summarizes stock option activity under the Company’s equity incentive plans:

	Outstanding Stock Options			Weighted-Average Exercise Price Per Share		Weighted-Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
	(in thousands, except per share amounts and years)
December 31, 2023		1,975		$	9.00		7.6	$	604
Granted		940		$	0.36
Exercised		—		$	—
Forfeited		(296	)	$	8.83
Expired		(165	)	$	11.39
Outstanding as of June 30, 2024		2,454		$	5.55		8.7	$	160
Exercisable as of June 30, 2024		1,378		$	8.40		8.2	$	63

Summary of Fair Value of Stock Options Granted for Employee and Non-Employee Awards

The fair value of stock options granted for employee and non-employee awards was estimated at the grant date using the Black-Scholes option pricing model based on the following assumptions:

	Six Months Ended June 30,
	2024	2023
Expected volatility	121.8%	110.3% - 111.6%
Expected term (years)	1.0	6.5
Risk-free interest rate	5.07%	3.4% - 3.4%
Expected dividend yield	0% - 0%	0% - 0%

Summary of Companies Restricted Stock Activity

The following table summarizes the Company’s restricted stock activity consisting of RSUs:

	Number of Restricted Stock (RSUs)			Weighted-Average Grant Date Fair Value Per Share
Outstanding and unvested as of December 31, 2023		7,516		$	27.14
Exercised/Released		(4,191	)	$	27.20
Cancelled/Forfeited		(1,032	)	$	26.16
Outstanding and unvested as of June 30, 2024		2,293		$	27.47

Summary of Total Stock-Based Compensation

The following table summarizes total stock-based compensation included in the Company’s consolidated statements of operations:

	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
	(in thousands)
Research and development	$	84	$	348	$	158	$	425
General and administrative		285		1,522		688		2,499
Total stock-based compensation	$	369	$	1,870	$	846	$	2,924