Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense

The provision for income tax expense includes the following as of December 31, 2023, 2022, and 2021:

	December 31,
	2023		2022		2021
Current:
Federal	$	—	$	—	$	—
State	—		36		—
Total	—		36		—
Deferred:
Federal	—		—		—
State	—		—		—
Total	—		—		—
Total Tax Expense	$	—	$	36	$	—

Schedule of Reconciliation of the Difference between the Benefit for Income Taxes and Income Taxes at the Statutory U.S. Federal Income Tax Rate

A reconciliation of the difference between the benefit for income taxes and income taxes at the statutory U.S. federal income tax rate is as follows for the years ended December 31, 2023, 2022, and 2021 (in thousands, except percentages):

	2023				2022				2021
	Amount		% of Pretax Earnings		Amount		% of Pretax Earnings		Amount		% of Pretax Earnings
Income tax benefit at statutory rate	$	(17,240)	21.0	%	$	36,163	21.0	%	$	(36,379)	21.0	%
State income taxes	(2,275)		2.8	%	441		0.2	%	(8,060)		4.7	%
Research and development credits	(3,726)		4.5	%	(3,312)		(1.9)	%	(1,565)		0.9	%
In process R&D	—		—	%	—		—	%	26,395		(15.2)	%
Permanent items	1,365		(1.7)	%	1,135		0.7	%	711		(0.4)	%
Provision to return adjustments	31		(0.1)	%	1,091		0.6	%	126		(0.1)	%
Effect of change in state tax rate	(1,091)		1.3	%	4,405		2.6	%	3,478		(2.0)	%
Removal of excess tax benefit	—		—	%	—		—	%	—		—	%
Increase in unrecognized tax benefits	603		(0.6)	%	828		0.5	%	439		(0.3)	%
Current year forfeitures	51		(0.1)	%	54		—	%	435		(0.3)	%
Change in valuation allowance	22,282		(27.1)	%	(40,769)		(23.7)	%	14,420		(8.3)	%
Net benefit	$	—	—	%	$	36.0	—	%	$	—	—	%

Schedule of Components of Deferred Tax Assets and Liabilities

The components of deferred tax assets and liabilities at December 31, 2023 and 2022 were as follows (in thousands):

	December 31,
	2023		2022
Deferred tax assets:
Domestic net operating loss carryforwards	$	90,340	$	84,147
Research and development expenses	1,812		1,520
Capitalized Section 174 expenses	23,541		12,425
License fees	11,005		11,509
Research and development credits	22,638		20,166
Capital loss carryforwards	448		428
Accrued bonuses	815		722
Share-based compensation	9,012		6,132
Other	959		1,333
Total gross deferred tax assets	160,570		138,382
Valuation allowance	(160,218)		(137,936)
Total deferred tax assets	352		446
Deferred tax liabilities:
Right-of-use asset	(352)		(446)
Total deferred tax liabilities	(352)		(446)
Total deferred tax assets and liabilities, net	$	—	$	—

Schedule of Uncertain Tax Benefit

Therefore, the Company recognized an uncertain tax benefit associated with the federal R&D credit carryover during the years ended December 31, 2023 and 2022, as follows (in thousands):

Balance at December 31, 2021	$	4,734
Increases related to 2022	828
Increases related to prior periods	—
Balance at December 31, 2022	5,562
Increases related to 2023	736
Decreases related to prior periods	(121)
Balance at December 31, 2023	$	6,177