Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Taxes

Schedule of components of the net deferred tax asset

The components of the net deferred tax asset are as follows (in thousands):

	December 31,
	2014			2013
Gross deferred tax assets:
Net operating loss carryovers	$	26,505		$	23,006
Accrued expenses	—			18
Contributions	5			1
Stock-based compensation	211			143
Research and development and other credits	3,075			2,693
Total gross deferred tax assets	29,796			25,861
Gross deferred tax liabilities:
Depreciation	(1		)	(2		)
Total gross deferred tax liabilities	(1		)	(2		)
Net deferred tax assets	29,795			25,859
Less: valuation allowance	(29,795		)	(25,859		)
Net deferred tax assets after valuation allowance	$	—		$	—

Schedule of reconciliation of income tax expense (benefit) at the statutory federal income tax rate and income taxes

	Year Ended December 31,
	2014		2013
Federal income tax expense at statutory rate	34.0	%	34.0	%
Permanent items	(5.4	)	(0.3	)
State income tax, net of federal benefit	3.8		5.0
State refundable credit	0.0		0.7
R&D tax credits	4.2		(3.3	)
Change in valuation allowance	(36.6	)	(35.4	)
Effective income tax rate	0.0	%	0.7	%