Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Significant Component of Deferred Tax Assets

Significant components of the Company’s deferred tax assets at December 31, 2022 and 2021 are as follows:

	December 31,
(in thousands)	2022			2021
Deferred tax assets:
Net operating loss carryforwards	$	171,070		$	164,486
Start-up and pre-clinical studies		17,204			21,705
Research and development credit carryforwards		40,116			39,817
Stock-based compensation		698			706
Capitalized acquisition costs		2,180			2,946
Lease liability		618			1,278
Depreciation		239			102
Capitalized research expenses		5,156			-
Other		27			156
		237,308			231,196
Less valuation allowance		(236,827	)		(230,119	)
Total deferred tax assets		481			1,077
Right-of-use asset		(481	)		(1,077	)
Total deferred tax liabilities	$	(481	)	$	(1,077	)
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)	2022			2021
Federal income tax at statutory rates		21	%		21	%
State income tax, net of federal tax benefit		3	%		3	%
Research and development credits		2	%		3	%
Research and development true-up		-2	%		0	%
Stock-based compensation		-1	%		-1	%
Federal/state rate change		-5	%		-2	%
Change in valuation allowance		-18	%		-24	%
Effective tax rate		0	%		0	%