Income taxes (Tables)

12 Months Ended

Dec. 31, 2016

Schedule of effective income tax rate reconciliation

The following table presents a reconciliation of income tax expense (benefit) computed at the statutory federal income tax rate to the effective income tax rate as reflected in the consolidated financial statements:



	Year Ended December 31, 2016		Year Ended December 31, 2015		Period from February 26, 2014 (Inception) to December 31, 2014
Federal income tax expense at statutory rate	35.0	%	35.0	%	35.0	%
State income tax, net of federal benefit	5.0	%	3.4	%	3.7	%
Permanent differences	0.0	%	(0.2	)%	(0.3	)%
Stock-based compensation	(2.6	)%	(6.3	)%	(5.3	)%
Research credits	1.9	%	1.8	%	1.2	%
Other, net	(0.1	)%	0.4	%	n/a
Change in valuation allowance	(39.2	)%	(34.1	)%	(34.3	)%
Effective tax rate	0.0	%	0.0	%	0.0	%

Schedule of deferred tax assets and liabilities

The following table presents the significant components of the Company's deferred tax assets and liabilities:



	December 31, 2016			December 31, 2015
Deferred tax assets:
U.S. and state net operating loss carryforwards	$	24,322,172		$	11,118,289
Accruals and other temporary differences	529,462			510,897
Amortization	32,171			33,824
Stock-based compensation	1,847,441			473,801
Tax credit carryforward	1,423,292			671,012
Total deferred tax assets	28,154,538			12,807,823
Less valuation allowance	(28,127,611		)	(12,688,401		)
Deferred tax assets	26,927			119,422
Deferred tax liabilities:
Stock-based compensation	(23,316		)	(110,366		)
Depreciation	(3,611		)	(9,056		)
Accruals and other temporary differences	—			—
Deferred tax liabilities	(26,927		)	(119,422		)
Net deferred tax assets	$	—		$	—