Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

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 34% for 2017 and 2016, as a result of the following (in thousands):

	Years ended December 31,
	2017			2016
U.S. federal income tax benefit at statutory rates	$	(6,286	)	$	(5,591	)
State income tax benefit, net of federal benefit		(565	)		(502	)
Research and experimentation credits		(303	)		(268	)
Change in tax rate		20,085			—
Deferred tax asset adjustment		37			65
Other		122			137
Change in valuation allowance		(13,151	)		6,159
Income tax benefit	$	(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,
	2017			2016
Net operating loss carryforwards	$	38,566		$	51,758
Charitable contribution carryforwards		455			552
Research and experimentation credits		1,682			1,440
Capitalized intangibles		608			781
Stock based compensation		148			193
Depreciation and amortization		1			6
Accrued compensation		168			35
Other		—			14
Total deferred tax assets		41,628			54,779
Valuation allowance		(41,628	)		(54,779	)
Net deferred tax assets	$	—		$	—