Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Loss before Provision for Income Taxes

Loss before the provision for income taxes consisted of the following (in thousands):

	Year Ended December 31,
	2019			2018
U.S. operations	$	(23,330	)	$	(21,132	)
Foreign operations		—			(5,483	)
Loss before provision for income taxes	$	(23,330	)	$	(26,615	)

Income Tax Provision Amount Computed by Applying Statutory Income Tax Rate

The income tax provision differs from the amount computed by applying the statutory income tax rate of 21% to pre-tax loss as follows (in thousands):

	Year Ended December 31,
	2019				2018
Tax (benefit) at statutory federal rate		21.0		%		21.0		%
State tax (benefit), net of federal benefit		7.1				4.6
Foreign tax rate differential		—				(4.3	)
Permanent differences		(0.6	)			(0.6	)
Research and development credits		1.3				1.0
Change in valuation allowance		(20.9	)			(15.9	)
Provision-to-return		—				(0.7	)
Expired NOLs, research and development credits, and    other carryfowards		(6.9	)			(2.2	)
Non-qualified stock option cancellations		(1.0	)			(2.9	)
Effective tax rate		—		%		—		%

Significant Components of Deferred Tax Assets

Significant components of the Company’s deferred tax assets for federal and state income taxes are as follows (in thousands):

	December 31,
	2019			2018
Deferred tax assets:
Federal and state net operating loss carry-forwards	$	119,015		$	114,254
Federal and state research credit carry-forwards		15,140			14,885
Capitalized research costs		6,081			6,134
Stock-based compensation		3,996			4,002
Lease liabilities		152			—
Property and equipment		77			79
Accrued liabilities		86			143
Gross deferred tax assets		144,547			139,497
Deferred tax liabilities:
Right-of-use assets		(152	)		—
Gross deferred tax liabilities		(152	)		—
Net deferred tax assets		144,395			139,497
Valuation allowance		(144,395	)		(139,497	)
Deferred tax assets, net of valuation allowance	$	—		$	—

Reconciliation of Unrecognized Tax Benefits

A reconciliation of the Company’s beginning and ending amount of unrecognized tax benefits is follows (in thousands):

	December 31,
	2019			2018
Unrecognized tax benefits at beginning of period	$	1,812		$	1,769
Increases related to current year tax positions		58			43
Decreases related to prior year tax positions		(23	)		—
Unrecognized tax benefits at the end of period	$	1,847		$	1,812