Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Taxes

Schedule of components of loss before income tax

The components of loss before income tax is as follows (in thousands):

	December 31,
	2022		2021		2020
Domestic	$	(41,307)	$	(43,241)	$	(5,995)
Foreign		—		—		—
	$	(41,307)	$	(43,241)	$	(5,995)

Schedule of reconciliation of the effective tax rate to the U.S. Federal statutory rate

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

	December 31,
	2022		2021		2020
Federal tax benefit at statutory rate	21	%	21	%	21	%
State tax, net of Federal benefit	8	%	9	%	14	%
Change in valuation allowance	(22)	%	(26)	%	(24)	%
Research and development tax credits	2	%	3	%	19	%
Share based Compensation	(1)	%	(1)	%	(10)	%
162(m) covered employees compensation limitation	—	%	—	%	(6)
FIN48 Reserve	—	%	(1)	%	(161)	%
Investment in Angel	(7)	%	(3)	%	174
Gain on transfer of intellectual property	—		—	%	(20)
Prior year federal true-up	—	%	(1)	%	(7)	%
Other	(1)	%	(1)		—
Effective income tax rate	0	%	0	%	0	%

Schedule of principal components of the net deferred tax assets

The principal components of the Company’s net deferred tax assets are as follows (in thousands)

	December 31,
	2022		2021		2020
Deferred tax assets
Net operating loss carryforwards	$	56,030	$	52,539	$	42,344
Tax credit carryforwards		9,888		9,181		7,894
Capitalized tax assets		155		125		63
Accruals		124		137		207
Stock compensation		5,487		5,006		4,942
Operating lease liability		728		1,021		646
IRC 174 capitalization		4,518		—		—
Other		21		12		47
Total deferred tax assets	$	76,951	$	68,021	$	56,143
Deferred tax liabilities
Operating lease right-of-use asset	$	(620)	$	(893)	$	(461)
Valuation allowance		(76,331)		(67,128)		(55,682)
Net deferred tax assets	$	—	$	—	$	—

Schedule of unrecognized tax benefits activity

	December 31,
	2022		2021		2020
Unrecognized tax benefits beginning of the period	$	12,504	$	12,157	$	1,885
Decrease related to the prior year		—		—		—
Increased related to the current year		216		347		10,272
Unrecognized tax benefits, end of the period	$	12,720	$	12,504	$	12,157