Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

The reconciliation of the federal statutory income tax rate to the Company’s effective income tax rate is as follows:

	Year Ended December 31,
	2020			2019
Income tax benefit at the federal statutory rate		21.0	%		21.0	%
State income taxes, net of federal benefit	3.2				1.1
Research and development tax credits	1.3				2.8
Other		(0.6	)		(0.3	)
Mark to market gain/loss	1.7				—
Change in valuation allowance		(26.6	)		(24.6	)
Total		—	%		—	%

The principal components of the Company’s net deferred tax assets consisted of the following (in thousands):

	December 31,
	2020			2019
Deferred tax assets
Federal and state net operating loss carryforwards	$	27,567		$	21,262
Research and development tax credits		4,887			4,140
Other		748			488
Gross deferred tax assets		33,202			25,890
Less: valuation allowance		(33,141	)		(25,841	)
Total deferred tax assets		61			49
Deferred tax liabilities
Depreciation		(61	)		(49	)
Total deferred tax liabilities		(61	)		(49	)
Net deferred tax assets	$	—		$	—

A reconciliation of the unrecognized tax benefit is as follows (in thousands):

	Year Ended December 31,
	2020		2019
Balance—beginning of year	$	1,406	$	873
Addition based on tax position related to current year		406		533
Addition based on tax position related to prior year		169		—
Balance—end of year	$	1,981	$	1,406