Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Significant Component of Deferred Tax Assets

Significant components of the Company’s deferred tax assets at December 31, 2020 and 2019 are as follows:

	December 31,
(in thousands)	2020			2019
Deferred tax assets:
Net operating loss carryforwards	$	147,004		$	124,115
Start-up and organizational costs		25,909			30,480
Research and development credit carryforwards		37,183			35,130
Stock compensation		1,478			1,087
Capitalized acquisition costs		3,691			4,501
Lease liability		1,225			626
Depreciation		71			176
Other		135			1,186
		216,696			197,301
Less valuation allowance		(215,513	)		(196,696	)
Total deferred tax assets		1,183			605
Deferred tax liabilities:
Right of use asset		(1,183	)		(605	)
Total deferred tax liabilities	$	(1,183	)	$	(605	)
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)	2020			2019			2018
Federal income tax at statutory rates		21	%		21	%		21	%
State income tax, net of federal tax benefit		3	%		3	%		4	%
Non-cash inducement warrant expense		0	%		-11	%		0	%
Research and development credits		3	%		1	%		2	%
Stock compensation		-1	%		0	%		-1	%
Research and development true-up		0	%		0	%		0	%
Officers compensation		0	%		0	%		-1	%
Other		0	%		-1	%		-2	%
Federal rate change		-2	%		0	%		3	%
Change in valuation allowance		-24	%		-13	%		-26	%
Effective tax rate		0	%		0	%		0	%