Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Benefit Attributable to Our Loss from Operations

Income tax benefit attributable to our loss from operations before income taxes differs from the amounts computed by applying the U.S. federal statutory income tax rate of 21% for 2018 and 34% for 2017, as a result of the following (in thousands):

	Years ended December 31,
	2018			2017
U.S. federal income tax benefit at statutory rates	$	(1,666	)	$	(6,286	)
State income tax benefit, net of federal benefit		(290	)		(565	)
Research and experimentation credits		(144	)		(303	)
Change in tax rate		—			20,085
Deferred tax asset adjustment		34			37
Other		134			122
Change in valuation allowance		1,901			(13,151	)
Income tax benefit	$	(31	)	$	(61	)

Net Deferred Tax Assets

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting and the amounts used for income tax purposes, as well as operating loss and tax credit carryforwards. The income tax effects of temporary differences and carryforwards that give rise to significant portions of the Company’s net deferred tax assets consisted of the following (in thousands):

	As of December 31,
	2018			2017
Net operating loss carryforwards	$	40,742		$	38,566
Charitable contribution carryforwards		433			455
Research and experimentation credits		1,796			1,682
Capitalized intangibles		409			608
Stock-based compensation		127			148
Depreciation and amortization		1			1
Accrued compensation		20			168
Other		1			—
Total deferred tax assets		43,529			41,628
Valuation allowance		(43,529	)		(41,628	)
Net deferred tax assets	$	—		$	—