Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Reconciliation of Expected Income Tax Benefit (Expense) Computed using Federal Statutory Income Tax Rate Effective Income Tax Rate

A reconciliation of the expected income tax benefit (expense) computed using the federal statutory income tax rate to the Company’s effective income tax rate was as follows:

	Year Ended December 31,
	2014			2013			2012
Income tax benefit computed at federal statutory tax rate		34.00	%		34.00	%		34.00	%
State taxes, net of federal benefit		5.05			4.67			5.19
Change in valuation allowance		(39.09	)		(39.43	)		(39.88	)
General business credits and other credits		1.33			4.28			0.86
Permanent differences		(1.29	)		(3.52	)		(0.17	)
Total		—	%		—	%		—	%

Deferred Tax Assets

The Company’s deferred tax assets consist of the following (in thousands):

	December 31,
	2014			2013
Deferred tax assets:
Net operating loss carryforwards	$	33,267		$	21,085
Research and development credit carryforwards		1,979			1,511
Accruals and other		948			333
Capitalized license and organization costs		73			79
Capitalized start-up costs		309			340
Total gross deferred tax asset		36,576			23,348
Deferred tax liability		(18	)		(77	)
Valuation allowance		(36,558	)		(23,271	)
Net deferred tax asset	$	—		$	—