Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Reconciliation of the Federal Statutory Income Tax Rate and the Company's Effective Income Tax Rate

A reconciliation of the federal statutory income tax rate and the Company’s effective income tax rate is as follows:

	Year Ended December 31,
	2023			2022			2021
Federal statutory income tax rate		(21.0	)%		(21.0	)%		(21.0	)%
State income taxes		(8.6	)		(8.3	)		(16.6	)
Research and development tax credits		(6.9	)		(5.3	)		(8.7	)
Stock-based compensation		1.6			(0.1	)		(16.8	)
Non-deductible officers' compensation		-			0.1			0.2
In-process research and development		-			2.5			-
Change in valuation allowance		34.9			32.1			62.9
Effective income tax rate		—	%		—	%		—	%

Summary of Company's Net Deferred Tax Assets (Liabilities)

The Company’s net deferred tax assets (liabilities) consisted of the following:

	December 31,
	2023			2022
	(in thousands)
Deferred tax assets:
Net operating loss carryforwards	$	258,664		$	229,375
Research and development credit carryforwards		151,333			101,326
Section 174 capitalized research		150,993			78,873
Operating lease liability		31,183			35,386
Deferred revenue		9,633			13,189
Stock-based compensation		30,408			22,512
Accruals and allowances		6,244			4,968
Prepaid rent		1,190			1,367
Equity investment adjustments		7,580			3,358
Intangibles, including in-process research and development		1,017			930
Capitalized start-up costs		249			296
Gross deferred tax assets		648,494			491,580
Deferred tax asset valuation allowance		(616,082	)		(454,793	)
Total deferred tax assets		32,412			36,787
Deferred tax liabilities:
Fixed assets		(1,221	)		(759	)
Operating lease right-of-use assets		(31,191	)		(36,028	)
Total deferred tax liabilities		(32,412	)		(36,787	)
Net deferred tax asset (liability)	$	-		$	-

The Tax Cuts and Jobs Act (“TCJA”) requires taxpayers to capitalize and amortize, rather than deduct, research and development expenditures under section 174 for tax years beginning after December 31, 2021. These rules became effective for the Company during the year ended December 31, 2022. As a result, the Company has capitalized research and development costs of $322.6 million and $365.8 million for the years ended December 31, 2022 and December 31, 2023, respectively. The Company will amortize these costs for tax purposes over 5 years if the research and development was performed in the U.S. and over 15 years if the research and development was performed outside the U.S.