Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Schedule of components of the net deferred income tax asset

The components of the net deferred income tax asset as of December 31, 2020 and 2019 are as follows (amounts in thousands):


	December 31,
	2020		2019
Deferred taxes:
Net operating loss carryforwards	$	90,842	$	96,378
Research and development credit carryforwards	13,603		13,404

Stock-based compensation	4,071		4,107
Accruals	352		414
Right-of-use asset	(508)		(742)
Lease liability	559		934
Capitalized start-up costs	775		855
Other	20		10
Gross deferred tax asset	109,714		115,360
Less: valuation allowance	(109,714)		(115,360)
Net deferred tax asset	$	—	$	—

Schedule of reconciliation of income tax expense (benefit) at the statutory federal income tax rate

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:


	December 31,
	2020		2019
Federal income tax benefit at statutory rate	21.0	%	21.0	%
State income tax, net of federal benefit	2.2	%	2.4	%
Permanent differences	(2.4)	%	(1.0)	%
Rate change	—	%	(8.7)	%
Research and development credit benefit	1.7	%	2.7	%
Change in valuation allowance	(22.5)	%	(16.4)	%
Effective income tax rate	—	%	—	%