Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Components of Provision for Income Taxes

The components of our provision for income taxes for the years ended December 31, 2023, 2022 and 2021, are as follows (in thousands):

	Year Ended December 31,
	2023		2022		2021
Current:
State	$	47	$	8	$	4
Foreign	500		—		—
Total current	547		8		4
Deferred:
Federal	—		—		—
Total deferred	—		—		—
Provision for income taxes	$	547	$	8	$	4

Schedule of Reconciliation of Effective Tax Rate

A reconciliation of the statutory federal income tax rate to our effective tax rate is as follows:

	Year Ended December 31,
	2023		2022		2021
Income tax at the federal statutory rate	21.0	%	21.0	%	21.0	%
State taxes, net of federal benefit	3.4		1.9		0.4
Tax credits	1.7		1.5		1.0
Stock based compensation	0.1		(2.3)		(1.3)
Foreign withholding tax	(0.8)		—		—
Executive compensation disallowed under IRC Sec 162(m)	(1.9)		(1.6)		(1.1)
Other	—		(0.8)		—
Change in valuation allowance	(24.3)		(19.7)		(20.0)
Income tax provision	(0.8)	%	—	%	—	%

Schedule of Components of Deferred Tax Assets

Significant components of our deferred tax assets are as follows as of December 31, 2023 and 2022 (in thousands):

	December 31,
	2023		2022
Deferred tax assets:
Amortization and depreciation	$	64,919	$	64,111
Net operating loss carryforwards	98,702		86,547
Tax credits	15,375		14,411
Stock-based compensation	6,946		5,244
Deferred royalty obligation	4,907		2,577
Other	6,707		4,909
Gross deferred tax assets	197,556		177,799
Valuation allowance	(196,197)		(175,670)
Deferred tax assets net of valuation allowance	1,359		2,129
Deferred tax liabilities:
Right-of-use asset	(1,359)		(2,129)
Other	—		—
Net deferred tax assets	$	—	$	—

Schedule of Reconciliation of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):

	December 31,
	2023		2022		2021
Balance at beginning of year	$	24,075	$	24,426	$	23,624
Additions based on tax positions related to current year	262		460		1,613
Additions based on tax positions related to prior year	99		—		—
Subtractions based on tax positions related to prior year	(811)		(811)		(811)
Balance at end of year	$	23,625	$	24,075	$	24,426