Income Taxes (Tables)

12 Months Ended

Dec. 31, 2024

Income Taxes [Abstract]

Loss Before Income Taxes

Loss before income taxes is comprised of (in thousands):

	Year Ended December 31,
	2024			2023			2022
United States	$	(460,712	)	$	(334,707	)	$	(258,493	)
Foreign		644			742			508
Loss before income taxes	$	(460,068	)	$	(333,965	)	$	(257,985	)

Income Tax Expense (Benefit)

Our income tax expense (benefit) was as follows (in thousands):

	Year Ended December 31,
	2024			2023			2022
Current:
Federal	$	(5,492	)	$	35,861		$	10,522
State		(848	)		(3,687	)		1,129
Foreign		169			147			86
Total current income tax expense (benefit)		(6,171	)		32,321			11,737
Deferred:
Federal		—			—			—
State		—			—			—
Total deferred income tax benefit		—			—			—
Total income tax expense (benefit)	$	(6,171	)	$	32,321		$	11,737

Reconciliation of Statutory to Effective Tax Rate

Our expense (benefit) for income taxes differs from the amount computed by applying the U.S. federal statutory rate to loss before income taxes. The sources and tax effects of the differences are as follows (in thousands):

	Year Ended December 31,
	2024					2023					2022
Pre-tax loss	$	(460,068	)			$	(333,965	)			$	(257,985	)
Statutory rate		(96,614	)	21.0	%		(70,133	)	21.0	%		(54,177	)	21.0	%
State income tax net of federal benefit		(11,889	)	2.6	%		(22,597	)	6.8	%		(13,622	)	5.3	%
Foreign		15		0.0	%		(22	)	0.0	%		(49	)	0.0	%
Net change in valuation allowance		152,590		(33.2	)%		175,388		(52.5	)%		104,951		(40.7	)%
Tax credits		(53,497	)	11.6	%		(67,131	)	20.1	%		(39,729	)	15.4	%
Tax rate change		10,815		(2.4	)%		1,023		(0.3	)%		(3,091	)	1.2	%
Non-deductible compensation		1,895		(0.4	)%		3,814		(1.1	)%		3,023		(1.2	)%
Other non-deductible items		188		0.0	%		327		(0.1	)%		57		0.0	%
Foreign-derived intangible income benefit		(21,071	)	4.6	%		(7,493	)	2.2	%		—		—
Stock-based compensation		10,732		(2.3	)%		19,546		(5.9	)%		14,030		(5.4	)%
Other		665		(0.2	)%		(401	)	0.1	%		344		(0.1	)%
Effective rate	$	(6,171	)	1.3	%	$	32,321		(9.7	)%	$	11,737		(4.5	)%

Deferred Tax Assets and Liabilities

Significant components of our deferred tax assets and liabilities as of December 31, 2024 and 2023 are as follows (in thousands):

	Year Ended December 31,
	2024			2023
Deferred Tax Assets:
Net operating loss carryovers	$	95,851		$	77,964
Tax credits		310,703			239,962
Deferred revenue		54,063			71,683
Stock-based compensation		82,660			77,468
Intangible and capital assets		93,541			104,380
Convertible debt		9,310			16,849
Capitalized research and development expenses		323,560			238,738
Long-term lease liabilities		41,481			43,718
Sale of future royalties		148,918			144,608
Other		14,024			10,343
Total deferred tax assets	$	1,174,111		$	1,025,713
Deferred Tax Liabilities:
Fixed assets		(5,719	)		(4,166	)
Right-of-use assets		(36,788	)		(42,007	)
Other		(1,896	)		(1,910	)
Net deferred tax asset	$	1,129,708		$	977,630
Valuation allowance		(1,129,708	)		(977,630	)
Total net deferred tax assets and liabilities	$	—		$	—

Gross Unrecognized Tax Benefits

The following table summarizes our gross unrecognized tax benefits (in thousands):

	Year Ended December 31,
	2024			2023			2022
Beginning balance of unrecognized tax benefits	$	43,298		$	56,567		$	55,085
Decrease for lapse of statute of limitations		(7,579	)		(14,993	)		—
Decrease for prior period tax positions		(110	)		(737	)		(267	)
Increase for prior period tax positions		1,902			429			259
Increase for current period tax positions		3,650			2,032			1,490
Ending balance of unrecognized tax benefits	$	41,161		$	43,298		$	56,567