Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Taxes [Abstract]

Income (Loss) Before Income Taxes

Income (loss) before income taxes is comprised of (in thousands):

	Year Ended December 31,
	2022			2021			2020
United States	$	(258,493	)	$	(29,966	)	$	(137,222	)
Foreign		508			818			2,670
Income (loss) before income taxes	$	(257,985	)	$	(29,148	)	$	(134,552	)

Income Tax Expense (Benefit)

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

	Year Ended December 31,
	2022		2021			2020
Current:
Federal	$	10,522	$	(200	)	$	(837	)
State		1,129		(690	)		3,782
Foreign		86		339			518
Total current income tax expense (benefit)		11,737		(551	)		3,463
Deferred:
Federal		—		—			341,728
State		—		—			—
Total deferred income tax benefit		—		—			341,728
Total income tax expense (benefit)	$	11,737	$	(551	)	$	345,191

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 income (loss) before taxes. The sources and tax effects of the differences are as follows (in thousands):

	Year Ended December 31,
	2022					2021					2020
Pre-tax income (loss)	$	(257,985	)			$	(29,148	)			$	(134,552	)
Statutory rate		(54,177	)	21.0	%		(6,121	)	21.0	%		(28,256	)	21.0	%
State income tax net of federal benefit		(13,622	)	5.3	%		4,278		(14.7	)%		(37,705	)	28.0	%
Foreign		(49	)	0.0	%		143		(0.5	)%		49		0.0	%
Net change in valuation allowance		104,951		(40.7	)%		2,885		(9.9	)%		460,898		(342.5	)%
Loss on debt transactions		—		—			262		(0.9	)%		—		—
Tax credits		(39,729	)	15.4	%		(23,198	)	79.6	%		(18,774	)	14.0	%
Deferred tax true-up		(20	)	0.0	%		(24	)	0.1	%		(206	)	0.2	%
Tax rate change		(3,091	)	1.2	%		12,838		(44.0	)%		(32,951	)	24.5	%
Non-deductible compensation		3,023		(1.2	)%		5,085		(17.4	)%		7,931		(5.9	)%
Other non-deductible items		57		0.0	%		84		(0.3	)%		193		(0.1	)%
Stock-based compensation		14,030		(5.4	)%		4,720		(16.2	)%		17,435		(13.0	)%
Impacts from Akcea Merger		—		—			—		—			(22,032	)	16.4	%
Other		364		(0.1	)%		(1,503	)	5.1	%		(1,391	)	0.9	%
Effective rate	$	11,737		(4.5	)%	$	(551	)	1.9	%	$	345,191		(256.5	)%

Deferred Tax Assets and Liabilities

Significant components of our deferred tax assets and liabilities as of December 31, 2022 and 2021 are as follows (in thousands):

	Year Ended December 31,
	2022			2021
Deferred Tax Assets:
Net operating loss carryovers	$	87,802		$	85,600
Tax credits		277,436			269,538
Deferred revenue		85,700			104,330
Stock-based compensation		86,983			86,611
Intangible and capital assets		104,649			92,542
Convertible debt		34,384			45,681
Interest expense limitation		—			6,996
Capitalized research and development expenses		119,635			—
Long-term lease liabilities		45,612			5,119
Other		15,813			9,929
Total deferred tax assets	$	858,014		$	706,346
Deferred Tax Liabilities:
Fixed assets		(4,475	)		(3,303	)
Right-of-use assets		(44,504	)		(4,159	)
Other		(313	)		(1,111	)
Net deferred tax asset	$	808,722		$	697,773
Valuation allowance		(808,722	)		(697,773	)
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,
	2022			2021			2020
Beginning balance of unrecognized tax benefits	$	55,085		$	54,163		$	69,784
Decrease for prior period tax positions		(267	)		(695	)		(24,154	)
Increase for prior period tax positions		259			263			7,023
Increase for current period tax positions		1,490			1,354			1,510
Ending balance of unrecognized tax benefits	$	56,567		$	55,085		$	54,163