CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Operating expenses:
Research and development	$ 9,836	$ 1,793	$ 19,371	$ 3,530
General and administrative	3,153	803	6,757	1,695
Total operating expenses	12,989	2,596	26,128	5,225
Loss from operations	(12,989)	(2,596)	(26,128)	(5,225)
Other income, net	118	2	218	8
Net loss	(12,871)	(2,594)	(25,910)	(5,217)
Accretion of convertible preferred stock		(676)		(1,333)
Net loss attributable to common stockholders	$ (12,871)	$ (3,270)	$ (25,910)	$ (6,550)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.62)	$ (1.52)	$ (1.27)	$ (3.04)
Weighted average common shares outstanding, basic and diluted (in shares)	20,663,088	2,154,953	20,417,301	2,154,953
Other comprehensive (loss) income:
Unrealized gain on marketable securities, net of tax of $0	$ 14	$ 3	$ 156	$ 6
Foreign currency translation adjustments	(16)		(6)
Total other comprehensive (loss) income	(2)	3	150	6
Comprehensive loss	$ (12,873)	$ (2,591)	$ (25,760)	$ (5,211)