INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Reconciliation of Income Tax Expense

The reconciliation between federal income taxes at the statutory U.S. federal income tax rate and the Company’s income tax expense for the year is as follows:  

(in thousands)	December 31, 2021		December 31, 2020
Tax benefit at statutory rate	$	(2,038)	$	(1,658)
Other	4		200
Stock based compensation	780		642
Offering issuance costs and changes in fair value of warrants and private placement option	(3,176)		(9,687)
Deferred tax valuation allowances	4,718		11,690
Research and development credit	(288)		(1,187)
Income tax expense	$	—	$	—

Significant Components of Deferred Taxes

Significant components of the Company’s deferred taxes as of December 31, 2021 and 2020 are as follows:

(in thousands)	December 31, 2021		December 31, 2020
Deferred tax assets (liabilities):
Net operating loss carryforward	$	100,346	$	94,132
Stock compensation	3,541		3,539
Intangible assets	7,156		7,682
Research and development credit	18,076		17,787
Operating lease assets	—		(213)
Operating lease liabilities	—		354
Other	(144)		976
Total deferred tax assets, net of deferred tax liabilities	128,975		124,257
Valuation allowance	(128,975)		(124,257)
Net deferred tax	$	—	$	—

Summary of Net Operating Loss Carryforwards

Net operating loss carryforwards and research tax credits as of December 31, 2021 and 2020 are as follows:

(in thousands)	December 31, 2021		December 31, 2020
U.S. federal income tax net operating loss carryforwards	$	477,839	$	448,250
U.K. net operating loss carryforwards	$	—	$	133
U.S. federal research tax credits	$	12,985	$	12,535
Texas research tax credits	$	5,091	$	5,252