Income taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income taxes

Schedule of components of income expense (benefit)

	Year ended December 31,
	2023		2022		2021
	(in thousands)
Current
Federal	$	1,248	$	—	$	—
State		160		16		—
Total current		1,408		16		—
Deferred
Federal		—		—		—
State		—		—		—
Total deferred		—		—		—
Total tax provision	$	1,408	$	16	$	—

Schedule of reconciliation of the expected income tax (benefit) computed using the federal statutory income tax rate to the effective income tax rate

	Year ended December 31,
	2023			2022			2021
Income tax computed at federal statutory tax rate		21.0	%		21.0	%		21.0	%
State taxes, net of federal benefit		5.4	%		5.2	%		6.6	%
Provision to return		0.9	%		3.2	%		4.9	%
General business credit carryovers		(0.4)	%		(3.5)	%		3.2	%
Non-deductible expenses		0.5	%		(4.6)	%		(3.8)	%
Other		(0.4)	%		—	%		—	%
Change in valuation allowance		(26.0)	%		(21.3)	%		(31.9)	%
Total		1.00	%		—	%		—	%

Schedule of principal components of the Company's deferred tax assets and liabilities

	As of December 31,
	2023		2022
	(in thousands)
Deferred tax assets:
Net operating loss carryforward	$	13,724	$	47,282
Tax credit carryforward		28,427		32,060
Lease liability		5,544		6,318
Deferred revenue		1,675		17,984
Stock compensation		5,157		4,630
Non-deductible accruals and reserves		2,613		1,603
Capitalized research expenses		31,347		14,351
Intangibles		554		610
Other temporary differences		—		(1)
Total deferred tax assets		89,041		124,837
Less valuation allowance		(82,612)		(117,416)
Net deferred tax assets		6,429		7,421
Deferred tax liabilities
Right of use assets		(3,691)		(4,231)
Depreciation and amortization		(2,738)		(3,190)
Other temporary differences		—		—
Net deferred taxes	$	—	$	—