Share-Based Compensation (Tables)

6 Months Ended

Jun. 30, 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 six months ended June 30, 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		(43,156	)		13.31
Outstanding as of June 30, 2024		2,858,042		$	10.74		5.04	$	1
Outstanding as of June 30, 2024 - vested and    expected to vest		2,858,042		$	10.74		5.04	$	1
Exercisable at June 30, 2024		2,540,372		$	10.44		4.85	$	—

Summary of Share-Based Compensation Expense

The Company recorded share-based compensation expense related to incentive stock options, nonqualified stock options, stock grants, and stock-based awards in the following expense categories of its consolidated statements of operations and comprehensive loss (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
Research and development expenses	$	729	$	589	$	1,419	$	1,387
General and administrative expenses		1,384		1,268		2,717		2,640
Total	$	2,113	$	1,857	$	4,136	$	4,027

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 during the six months ended June 30, 2024:

	Number of RSU Shares			Weighted Average Grant Date Fair Value
Outstanding as of December 31, 2023		5,368,807		$	2.45
Granted		3,410,996			1.56
Vested and released		(1,009,459	)		2.60
Forfeited or cancelled		(149,600	)		1.93
Outstanding as of June 30, 2024		7,620,744		$	2.04

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 six months ended June 30, 2024:

	Number of Inducement PSU Shares		Weighted Average Grant Date Fair Value
Outstanding as of December 31, 2023		69,999	$	1.08
Granted		—		—
Vested and released		—		—
Forfeited or cancelled		—		—
Outstanding as of June 30, 2024		69,999	$	1.08