Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2024

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

Summary of Shares of Common Stock Reserved for Issuance

Shares of common stock reserved for issuance under the Company’s equity incentive plans were as follows:

	March 31, 2024
Outstanding stock awards		9,261,193
Reserved for future award grants		5,528,052
Reserved for future ESPP		583,756
Total common stock reserved for stock awards		15,373,001

Service-Based

Summary of Stock Option Activity

A summary of the Company’s service-based stock option activity (excluding performance-based stock option activity, which is presented separately below) for the three months ended March 31, 2024 is as follows:

	Outstanding Service-Based Options
(in thousands, except share and per share data)	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Balance—December 31, 2023		5,805,586		$	7.40		6.90	$	64
Options granted		2,400,500			1.59
Options exercised		—			—
Options forfeited or expired		(256,904	)		7.60
Balance—March 31, 2024		7,949,182		$	5.64		7.85	$	46
Options vested and exercisable as of March 31, 2024		3,321,228		$	9.62		5.72	$	—

Summary of Weighted-average Assumptions Used in Determination of Fair Value of Stock Options

	Three Months Ended March 31,
	2024	2023
Expected term (in years)	5.50 - 6.08	5.77
Volatility	72.63 - 80.28%	78.98%
Risk-free interest rate	3.88 - 4.33%	3.58%
Dividend yield	–%	–%

Summary of Restricted Stock Units Activity

A summary of the Company’s RSU activity for the three months ended March 31, 2024 is as follows:

	Unvested Restricted Stock Units
(in thousands, except share and per share data)	Number of Shares			Weighted- Average Grant Date Fair Value		Aggregate Fair Value
Balance—December 31, 2023		1,253,826		$	8.99	$	2,633
RSUs granted		—			—
RSUs vested		(33,505	)		26.87		49
RSUs forfeited		(172,810	)		9.45
Balance—March 31, 2024		1,047,511		$	8.34	$	1,561

Stock Based Compensation Expense by Award Type and Function

The following is a summary of stock-based compensation expense by award type (in thousands):

	Three Months Ended March 31,
	2024		2023
Service-based stock options	$	1,215	$	1,343
Performance-based stock options		6		—
RSUs		1,408		2,123
ESPP		58		229
Total stock-based compensation expense	$	2,687	$	3,695

The following is a summary of stock-based compensation expense by function (in thousands):

	Three Months Ended March 31,
	2024		2023
Cost of revenue	$	154	$	490
Research and development		947		1,245
Selling, general and administrative		1,586		1,960
Total stock-based compensation expense	$	2,687	$	3,695

2019 Employee Stock Purchase Plan | Performance-Based Stock Option

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

Summary of Stock Option Activity

A summary of the Company's performance-based stock option activity for the three months ended March 31, 2024 is as follows:

	Outstanding Performance-Based Options
(in thousands, except share and per share data)	Number of Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Balance—December 31, 2023		—	$	—		—	$	—
Options granted		264,500		1.61
Balance—March 31, 2024		264,500	$	1.61		9.96	$	—
Options vested and exercisable as of March 31, 2024		—