Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2024

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Stock Option Activity

The following table summarizes stock option activity under the Equity Plans (excluding RSUs) during the year ended December 31, 2024:

	2017 Plan			2019 Inducement Plan			Total Number of Stock Options
Outstanding as of December 31, 2023		2,569,421			296,173			2,865,594
Granted		35,604			—			35,604
Exercised		—			—			—
Forfeited or cancelled		(46,439	)		(39,909	)		(86,348	)
Outstanding as of December 31, 2024		2,558,586			256,264			2,814,850

The following table summarizes details regarding stock options granted under the Equity Plans (excluding RSUs) for the year ended December 31, 2024:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Contractual Term		Aggregate Intrinsic Value
						(in years)		(in thousands)
Outstanding as of December 31, 2023		2,865,594		$	10.89		5.76	$	1
Granted		35,604			1.52
Exercised		—			—
Forfeited or cancelled		(86,348	)		12.81
Outstanding as of December 31, 2024		2,814,850		$	10.71		4.45	$	0
Outstanding as of December 31, 2024 - vested and expected to vest		2,814,850		$	10.71		4.45	$	0
Exercisable at December 31, 2024		2,667,152		$	10.60		4.33	$	0

Summary of Assumptions Used to Determine Fair Value of Stock Option Awards Granted to Employees and Directors

The assumptions that the Company used in the Black-Scholes option-pricing model to determine the fair value of stock option awards granted to employees and directors were as follows, presented on a weighted average basis:

	Year Ended December 31,
	2024			2023
Risk-free interest rate		3.8	%		4.0	%
Expected term (in years)		5.5			5.5
Expected volatility		90.2	%		90.7	%
Expected dividend yield		0.0	%		0.0	%

Summary of Share-Based Compensation Expense

The Company recorded share-based compensation expense, for both RSUs and stock options in the following expense categories of its consolidated statements of operations and comprehensive loss (in thousands):

	Year Ended December 31,
	2024		2023
Research and development expenses	$	2,605	$	2,654
General and administrative expenses		5,188		5,278
Total	$	7,793	$	7,932

Performance Shares [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Activity of Options and RSUs of Performance-Based Options

The following table summarizes Inducement PSU activity under the Equity Plans during the year ended December 31, 2024:

	Number of Performance Based Option Shares			Weighted Average Grant Date Fair Value
Outstanding as of December 31, 2023		69,999			1.08
Granted		—			—
Vested and released		(69,999	)		1.08
Forfeited or cancelled		—			—
Outstanding as of December 31, 2024		—			—

Restricted Stock Units (RSUs) [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Activity of Options and RSUs of Performance-Based Options

The following table summarizes RSU activity under the Equity Plans (excluding performance-based RSUs) during the year ended December 31, 2024:

	Number of RSU Shares			Weighted Average Grant Date Fair Value
Outstanding as of December 31, 2023		5,368,807		$	2.45
Granted		3,638,496			1.54
Vested and released		(1,523,848	)		2.72
Forfeited or cancelled		(1,444,723	)		1.88
Outstanding as of December 31, 2024		6,038,732		$	1.97