Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

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,
	2015		2014
Gross deferred tax assets:
Net operating loss carryforwards	$	37,051	$	26,505
Accrued expenses		29		—
Contributions		6		5
Deferred expenses		23		—
Stock‑based compensation		826		211
Research and development and other credits		4,123		3,075
Total gross deferred tax assets		42,058		29,796
Gross deferred tax liabilities:
Depreciation		(2)		(1)
Total gross deferred tax liabilities		(2)		(1)
Net deferred tax assets		42,056		29,795
Less: valuation allowance		(42,056)		(29,795)
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,
	2015		2014
Federal income tax expense at statutory rate	34.0	%	34.0	%
Permanent items	(1.0)		(5.4)
State income tax, net of federal benefit	7.1		3.8
R&D tax credits	4.2		4.2
Other	5.0		—
Change in valuation allowance	(49.3)		(36.6)
Effective income tax rate	0.0	%	0.0	%