Income taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income taxes

Schedule of components of income expense (benefit)

	Year ended December 31,
	2022		2021		2020
	(in thousands)
Current
Federal	$	—	$	—	$	—
State		16		—		—
Total current		16		—		—
Deferred
Federal		—		—		—
State		—		—		—
Total deferred		—		—		—
Total tax provision	$	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,
	2022			2021			2020
Income tax computed at federal statutory tax rate		21.0	%		21.0	%		21.0	%
State taxes, net of federal benefit		5.2	%		6.6	%		(2.3)	%
Provision to return		3.2	%		4.9	%		—	%
General business credit carryovers		(3.5)	%		3.2	%		(20.6)	%
Non-deductible expenses		(4.6)	%		(3.8)	%		5.0	%
Other		—	%		—	%		1.9	%
Change in valuation allowance		(21.3)	%		(31.9)	%		(5.0)	%
Total		—	%		—	%		—	%

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

	As of December 31,
	2022		2021
	(in thousands)
Deferred tax assets:
Net operating loss carryforward	$	47,282	$	56,756
Tax credit carryforward		32,060		30,122
Lease liability		6,318		12,012
Deferred revenue		17,984		11,485
Stock compensation		4,630		7,784
Non-deductible accruals and reserves		1,603		1,507
Capitalized research expenses		14,351		—
Intangibles		610		664
Other temporary differences		(1)		—
Total deferred tax assets		124,837		120,330
Less valuation allowance		(117,416)		(107,563)
Net deferred tax assets		7,421		12,767
Deferred tax liabilities
Right of use assets		(4,231)		(9,128)
Depreciation and amortization		(3,190)		(3,632)
Other temporary differences		—		(7)
Net deferred taxes	$	—	$	—