Annual report pursuant to Section 13 and 15(d)

Income Taxes (Tables)

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes and operating loss and credit carryforwards. Significant components of our deferred tax assets are as follows (in thousands):

	December 31,
	2017		2016
Deferred tax assets:
Net operating loss carryforwards	$	62,295	$	87,267
Research credit carryforwards		15,873		14,322
Other, net		1,705		2,637
Total deferred tax assets		79,873		104,226
Valuation allowance		(79,873)		(104,226)
Net deferred tax assets	$	—	$	—

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The provision for income taxes consists of state minimum taxes due. The effective tax rate of our provision (benefit) for income taxes differs from the federal statutory rate as follows (in thousands):

	Year Ending December 31,
	2017		2016		2015
Computed at 34%	$	(4,832)	$	1,758	$	(3,840)
State taxes		(157)		(187)		(268)
Change in valuation allowance		(28,555)		(4,439)		2,740
Other		388		659		(20)
Revaluation of warrant liability		(210)		(280)		1,534
Research and development credits		(250)		(252)		(146)
Net operating loss carryforward expirations		1,007		2,741		—
Impact of 2017 Tax Act		32,609		—		—
Total	$	—	$	—	$	—