Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Schedule of Reconciliation of Differences Between Federal Income Tax Rate and Effective Tax Rate

The following reconciles the differences between income taxes computed at the federal income tax rate and the provision for income taxes:

	Year Ended December 31,
	2021		2020		2019
Expected income tax benefit at the federal statutory rate	21.0	%	21.0	%	21.0	%
State taxes, net of federal benefit	0.0		0.0		0.0
Change in federal statutory rate	0.0		0.0		0.0
Non-deductible stock compensation	(3.1)		0.2		0.0
Non-deductible items and other	(1.7)		(3.6)		(2.8)
Federal and state credits	0.7		0.5		0.6
Change in valuation allowance	(16.9)		(18.1)		(18.8)
Total	0.0	%	0.0	%	0.0	%

Schedule of Deferred Tax Assets

The principal components of the Company’s net deferred tax assets consisted of the following at December 31, 2021 and 2020 (in thousands):

	Year Ended December 31,
	2021		2020
Deferred tax assets
Net operating loss carryforwards	$	140,581	$	121,346
Research and development tax credits	9,149		6,949
Reserves and accruals	4,781		4,984
Operating lease liability	2,615		2,588
Other	6,738		4,702
Total deferred tax assets	163,864		140,569
Less: Valuation allowance	(161,487)		(138,214)
Net deferred tax assets	2,377		2,355
Deferred tax liabilities
Right-of-use assets	(2,377)		(2,355)
Total deferred tax liabilities	(2,377)		(2,355)
Net deferred tax assets	$	—	$	—

Schedule of Unrecognized Tax Benefits

At December 31, 2021 and 2020, the Company’s unrecognized tax benefits consist of the following (in thousands):

	Year Ended December 31,
	2021		2020
Unrecognized tax benefit, beginning of period	$	2,681	$	2,158
Gross increases — current year tax positions	704		548
Gross increases — prior year tax positions	—		—
Gross decreases — prior year tax positions	(28)		(25)
Unrecognized tax benefit, end of period	$	3,357	$	2,681