Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Schedule of Geographical Breakdown of Loss Before Provision for Income Taxes

The geographical breakdown of loss before provision for income taxes is as follows:

	Year Ended December 31,
	2015			2014			2013
	(in thousands)
United States	$	(53,376	)	$	(23,872	)	$	(6,832	)
International		171			1			—
Loss before provision for income taxes	$	(53,205	)	$	(23,871	)	$	(6,832	)

Components of Provision for Income Taxes

The components of the provision for income taxes are as follows:

	Year Ended December 31,
	2015			2014			2013
	(in thousands)
Current tax provision:
Federal	$	—		$	—		$	—
State		—			—			—
Foreign		59			4			—
Total current tax provision		59			4			—
Deferred tax provision (benefit):
Foreign		(4	)		(2	)		—
Total deferred tax provision (benefit)	$	(4	)	$	(2	)	$	—
Total provision for income taxes	$	55		$	2		$	—

Reconciliation Between Income Taxes Computed at the Federal Statutory Income Tax Rate and the Provision for Income Taxes

The reconciliation between income taxes computed at the federal statutory income tax rate and the provision for income taxes is as follows:

	Year Ended December 31,
	2015			2014			2013
	(in thousands)
Federal statutory rate		34.0	%		34.0	%		34.0	%
Effect of:
Change in valuation allowance		(27.8	)		(37.3	)		(23.1	)
Federal tax credit		2.6			1.8			1.8
State income tax benefit, net of federal benefit		2.9			4.0			2.2
Conversion costs		—			—			(13.5	)
Change in fair value of preferred stock warrants		(11.1	)		(2.0	)		(1.1	)
Other permanent items		(0.7	)		(0.5	)		(0.3	)
Total provision for income taxes		(0.1	)%		—	%		—	%

Components of the Deferred Tax Assets

The components of the deferred tax assets are as follows:

	December 31,
	2015			2014
	(in thousands)
Deferred tax assets:
Net operating loss carryforwards	$	21,482		$	8,941
Research and development credits		1,923			649
License fee		3,413			3,880
Other		1,649			177
Gross deferred tax assets		28,467			13,647
Valuation allowance		(28,448	)		(13,645	)
Total deferred tax assets		19			2
Deferred tax liabilities:
Other		10			—
Total deferred tax liabilities		10			—
Total net deferred tax assets	$	9		$	2

Unrecognized Tax Benefits

The activity related to the gross amount of unrecognized tax benefits is as follows:

	Year Ended December 31
	2015			2014
	(in thousands)
Beginning balance	$	162		$	58
Increases based on tax positions related to prior years		—			—
Decreases based on tax positions related to prior years		(77	)		—
Increases based on tax positions in current year		147			104
Settlement		—			—
Lapse of statute of limitations		—			—
Ending balance	$	232		$	162