Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Summary of Difference Between Provision for Income Taxes and Amounts Computed by Applying Statutory Federal Income Tax Rate to Income Before Income Taxes

The difference between the Company’s provision for income taxes and the amounts computed by applying the statutory federal income tax rate to income before income taxes is as follows (in thousands):

	Year Ended December 31,
	2018			2017			2016
Tax provision derived by applying the federal statutory rate to income before income taxes	$	(9,313	)	$	(9,260	)	$	(7,377	)
Permanent differences and other		264			296			333
Federal tax credits		(1,211	)		(1,294	)		(1,921	)
State tax credits		464			(284	)		(404	)
Change in tax rate		—			7,869			—
Change in the valuation allowance		9,796			2,673			9,369
Income tax expense /(benefit)	$	—		$	—		$	—

Components of Deferred Tax Assets and Liabilities

The components of the deferred tax assets and liabilities consist of the following (in thousands):

	December 31,
	2018			2017
Deferred tax assets
Net operating loss carryforward	$	20,276		$	12,170
Intangible assets		38			29
Accrued expense		508			333
Stock-based compensation		682			386
Federal tax credits		7,260			5,572
State tax credits		359			824
Other		73			75
Total deferred tax assets		29,196			19,389
Deferred tax liabilities
Depreciable assets	$	(74	)	$	(63	)
Total deferred tax liabilities		(74	)		(63	)
Less: Valuation allowance		(29,122	)		(19,326	)
Deferred tax assets, net	$	—		$	—