Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Taxes

Schedule of loss before income taxes by jurisdiction

	Year Ended December 31,
(In thousands)	2023		2022		2021
U.S. operations	$	(88,848)	$	(86,908)	$	(90,865)
Foreign operations		—		—		—
Loss before income taxes	$	(88,848)	$	(86,908)	$	(90,865)

Reconciliation of statutory to effective rate

	Year Ended December 31,
	2023		2022		2021
Federal statutory income tax rate	(21.0)	%	(21.0)	%	(21.0)	%
State taxes, net of federal benefit	(1.7)		(2.3)		(7.7)
Impact of state rate changes	17.7		—		—
Research and development tax credits	(5.9)		(4.3)		(3.0)
Excess equity compensation tax benefit, net of officer limitation	0.6		0.2		(3.9)
Revaluation of contingent consideration	(6.3)		1.1		5.6
Non-deductible royalty payments	4.3		—		—
Change in deferred tax asset valuation allowance	11.7		26.3		30.0
Other	0.2		—		—
Effective income tax rate	(0.4)	%	—	%	—	%

Schedule of deferred tax assets and liabilities

		December 31,
(In thousands)	2023		2022
Deferred tax assets:
Net operating loss carryforwards	$	119,155	$	120,554
Capitalized start-up costs		3,812		5,506
Research and development tax credit carryforwards		20,505		15,233
Section 174 research and development capitalization		30,984		19,639
Capitalized research and development expense		2,359		5,448
Stock‑based compensation expense		18,055		19,432
Accrued compensation		1,219		1,146
Lease liabilities		774		558
Other		407		534
Total deferred tax assets		197,270		188,050
Deferred tax liabilities:
Property and equipment		(187)		(137)
Intangible asset		—		(1,576)
Right-to-use assets		(853)		(651)
Other		(1,106)		(1,365)
Total deferred tax liabilities		(2,146)		(3,729)
Valuation allowance		(195,124)		(184,688)
Deferred tax liabilities, net	$	—	$	(367)

Changes in deferred tax asset valuation allowance

		Year Ended December 31,
(In thousands)		2023		2022		2021
Valuation allowance at beginning of year	$	(184,688)	$	(161,824)	$	(134,559)
Decreases recorded as benefit to income tax provision		—		—		—
Increases recorded to income tax provision		(10,436)		(22,864)		(27,265)
Valuation allowance as of end of year	$	(195,124)	$	(184,688)	$	(161,824)