Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Significant Component of Deferred Tax Assets

Significant components of the Company’s deferred tax assets at December 31, 2023 and 2022 are as follows:

	December 31,
(in thousands)	2023			2022
Deferred tax assets:
Net operating loss carryforwards	$	148,009		$	171,070
Start-up and pre-clinical studies		13,754			17,204
Research and development credit carryforwards		39,838			40,116
Stock-based compensation		681			698
Capitalized acquisition costs		1,570			2,180
Lease liability		—			618
Depreciation		1			239
Capitalized research expenses		7,176			5,156
Other		2			27
		211,031			237,308
Less valuation allowance		(211,031	)		(236,827	)
Total deferred tax assets		—			481
Right-of-use asset		—			(481	)
Total deferred tax liabilities	$	—		$	(481	)
Net deferred taxes	$	—		$	—

Reconciliation of Income Tax Expense (Benefit)

A reconciliation of income tax expense (benefit) at the statutory federal income tax rate and income taxes as reflected in the financial statements is as follows:

	Year Ended December 31,
(in thousands)	2023			2022
Federal income tax at statutory rates		21	%		21	%
State income tax, net of federal tax benefit		(92	)%		3	%
Research and development credits		2	%		2	%
Research and development true-up		(1	)%		(2	)%
Stock-based compensation	—%				(1	)%
Federal/state rate change		(3	)%		(5	)%
Change in valuation allowance		73	%		(18	)%
Effective tax rate		—	%		—	%