Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Income before Income Tax

The components of loss before income taxes are as follows (in thousands):

	December 31,			December 31,
	2023			2022
U.S. loss before taxes	$	(48,590	)	$	(66,750	)
Foreign income before taxes		2			3
Loss before income taxes	$	(48,588	)	$	(66,747	)

Schedule of Components of Income Tax Expense (Benefit)

Income tax expense for the years ended December 31, 2023 and 2022 consists of the following (in thousands):

	Year ended December 31,
	2023			2022
Current:
Federal	$	—		$	—
State		21			8
Foreign		(1	)		1
		20			9
Deferred:
Federal		(9,527	)		(11,366	)
State		(3,266	)		(3,542	)
Foreign		—			—
		(12,793	)		(14,908	)
Change in valuation allowance		12,793			14,908
Income tax expense	$	20		$	9

Schedule of Deferred Tax Assets and Liabilities

The significant components that comprised the Company’s net deferred taxes are as follows (in thousands):

	Year ended December 31,
Deferred tax assets:	2023			2022
Net operating loss	$	73,600		$	70,179
Amortization		81			99
R&D expenditures capitalization		10,923			4,879
Stock-based compensation		3,292			2,960
Research and development credit		11,271			9,202
Right-of-use liability		752			1,204
Depreciation		1,035			779
Other		2,934			2,332
Gross deferred tax assets		103,888			91,634
Less: valuation allowance		(103,242	)		(90,471	)
Total net deferred tax assets	$	646		$	1,163
Deferred tax liabilities:
Right-of-use asset		(646	)		(1,163	)
Total deferred tax liabilities		(646	)		(1,163	)
Net deferred tax assets	$	—		$	—

Schedule of Effective Income Tax Rate Reconciliation

A reconciliation of the provision for income taxes with the expected income tax computed by applying the federal statutory income tax rate to loss before provision for income taxes was calculated as follows (amounts in thousands):

	December 31, 2023						December 31, 2022
	Rate			Amount			Rate			Amount
Income tax provision at the federal statutory tax rate		21.0	%	$	(10,203	)		21.0	%	$	(14,017	)
State taxes, net of federal benefit		4.1	%		(1,992	)		3.5	%		(2,358	)
Research and development credits		3.7	%		(1,805	)		1.9	%		(1,269	)
Stock-based compensation		(0.3	)%		150			(2.4	)%		1,625
Other non-deductible permanent items		(0.5	)%		246			(0.2	)%		105
Expired tax attributes		(2.2	)%		1,070			(1.5	)%		988
Other		0.5	%		(239	)		0.0	%		27
Change in valuation allowance		(26.3	)%		12,793			(22.3	)%		14,908
Income tax expense		0.0	%		20			0.0	%	$	9

Schedule of Unrecognized Tax Benefits [Roll Forward]

The following reconciliation of the beginning and ending amount of gross unrecognized tax benefits, excluding interest and penalties, is as follows (in thousands):

	Year ended December 31,
	2023		2022
Beginning balance of unrecognized tax benefits	$	3,494	$	3,013
Additions for current year tax positions		683		481
Reductions for prior year tax positions		67		—
Ending balance	$	4,244	$	3,494