Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Schedule of Loss Before Income Taxes

Loss Before Income Taxes

The domestic and foreign components of loss before income taxes were as follows (in thousands):

	Year Ended December 31,
	2022			2021			2020
United States	$	(36,416	)	$	(44,321	)	$	(28,803	)
Foreign		251			142			87
	$	(36,165	)	$	(44,179	)	$	(28,716	)

Reconciliation of U.S. Federal Statutory Income Tax Rate to Company's Effective Income Tax Rate

A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate is as follows:

	Year Ended December 31,
	2022			2021			2020
Federal statutory income tax rate		(21.0	)%		(21.0	)%		(21.0	)%
State taxes, net of federal benefit		(5.4	)%		(6.9	)%		(5.7	)%
Federal and state research and development tax    credits		(5.4	)%		(2.4	)%		(3.6	)%
Nondeductible items		(2.8	)%		(3.2	)%		(0.2	)%
Deferred tax effect of change in state blended rate		16.2	%		(1.7	)%		7.8	%
Return to provision		2.6	%		1.1	%		1.7	%
Other		0.1	%		(0.2	)%		0.0	%
Change in deferred tax asset valuation allowance		15.8	%		34.3	%		20.9	%
Effective income tax rate		0.1	%		0.0	%		(0.1	)%

Schedule of Net deferred Tax Assets

Net deferred tax assets consisted of the following (in thousands):

	December 31,
	2022			2021
Deferred tax assets:
Net operating loss carryforwards	$	92,445		$	94,672
Capitalized research and development expense		8,109			4,291
Research and development tax credit carryforwards		13,565			12,186
Accrued expenses		2,994			2,528
Stock-based compensation expense		3,492			2,254
Lease liability		2,218			2,299
Section 163(j) interest		754			—
Other		483			170
Total deferred tax assets		124,060			118,400
Deferred tax liabilities:
Other		(885	)		(674	)
Right-of-use assets		(1,284	)		(1,562	)
Total deferred tax liabilities		(2,169	)		(2,236	)
Valuation allowance		(121,891	)		(116,164	)
Net deferred tax assets	$	—		$	—

Summary Changes in the Valuation Allowance for Deferred Tax Assets

Changes in the valuation allowance for deferred tax assets during the year ended December 31, 2022 related primarily to the capitalization of research and development costs required under Section 174 and current year federal and net operating losses generated, partially offset by a decrease in deferred tax assets related to state net operating loss carryforwards due to a change in the state effective tax rate. Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2021 and 2020 related primarily to the increase in net operating loss carryforwards in 2021 and 2020. The changes in the valuation allowance were as follows (in thousands):

	Year Ended December 31,
	2022			2021			2020
Valuation allowance as of beginning of year	$	(116,164	)	$	(101,029	)	$	(95,024	)
Decreases recorded as benefit to income tax provision		—			—			—
Increases recorded to income tax provision		(5,727	)		(15,135	)		(6,005	)
Valuation allowance as of end of year	$	(121,891	)	$	(116,164	)	$	(101,029	)