Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Summary of reconciliation of income taxes computed using the U.S. federal statutory rate

A reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations follows (in thousands):

	Year Ended December 31,
	2021			2020
U.S.	$	(51,686	)	$	(77,884	)
International		39			82
Loss before benefit from income taxes	$	(51,647	)	$	(122,406	)
Income tax benefit using U.S. federal statutory rate	$	(10,846	)	$	(16,338	)
State income taxes, net of federal benefit		(3,631	)		(5,619	)
Non-deductible share-based compensation		(911	)		16
Share-based compensation - shortfalls/(windfalls)		946			1,047
Permanent differences		(420	)		(94	)
PPP loan forgiveness		(748	)		—
Tax credits		(805	)		(2,469	)
Other		(9	)		(16	)
Change in valuation allowance		16,424			23,473
	$	—		$	—

Summary of deferred tax assets (liabilities)

Deferred tax assets (liabilities) consist of the following as of December 31, 2021 and 2020 (in thousands):

	Year Ended December 31,
	2021			2020
Deferred tax assets:
Net operating loss carryforwards	$	43,700		$	27,007
Tax credit carryforwards		8,044			7,185
Share-based compensation		7,702			5,890
Operating lease - liability		—			11,536
Property and equipment		(1	)		1,362
Capitalized research and development		11,147			12,684
Accruals and reserves		91			518
Other		4			—
Total deferred tax assets	$	70,687		$	66,182
Deferred tax liabilities:
Operating lease - right of use asset	$	(383	)	$	(11,857	)
Prepaid sublease termination		(758	)		(1,203	)
Total deferred tax liabilities		(1,141	)		(13,060	)
Net deferred tax assets		69,546			53,122
Valuation allowance		(69,546	)		(53,122	)
Net deferred tax assets	$	—		$	—