Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Taxes

Summary of reconciliation of federal statutory income tax rate to the Company's effective income tax rate

	December 31,
	2018		2017
Expected income tax benefit at the federal statutory rate	21.0	%	34.0	%
State taxes, net of federal benefit	6.5		6.5
Research and development credit, net	7.2		4.7
Non-deductible items	(2.2)		(5.3)
Prior year provision to return adjustments	(7.7)		4.1
Tax rate reduction due to the Tax Act	—		(15.6)
Other	0.3		(2.9)
Change in valuation allowance	(25.1)		(25.5)
Total	—	%	—	%

Summary of components of deferred tax assets

The principal components of the Company’s deferred tax assets consisted of the following as of December 31, 2018 and 2017 (in thousands):

	December 31,
	2018		2017
Deferred tax assets:
Federal and state net operating loss carryforwards	$	11,946	$	6,176
Research and development tax credits		3,393		1,283
Charitable contribution carryforwards		165		153
Accruals		290		135
Other		23		4
Gross deferred tax assets		15,817		7,751
Less: valuation allowance		(15,525)		(7,491)
Total deferred tax assets	$	292	$	260
Deferred tax liabilities:
Depreciation and amortization	$	(292)	$	(260)
Gross deferred tax liabilities	$	(292)	$	(260)
Net deferred tax assets	$	—	$	—