CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Operating expenses:
Research and development	$ 7,965	$ 9,836	$ 15,737	$ 19,371
General and administrative	7,330	3,153	12,488	6,757
Total operating expenses	15,295	12,989	28,225	26,128
Loss from operations	(15,295)	(12,989)	(28,225)	(26,128)
Other income, net	457	118	828	218
Net loss	$ (14,838)	$ (12,871)	$ (27,397)	$ (25,910)
Net loss per share, basic and diluted (in dollars per share)	$ (0.56)	$ (0.62)	$ (1.04)	$ (1.27)
Weighted average common shares outstanding, basic and diluted (in shares)	26,594,854	20,663,088	26,339,250	20,417,301
Other comprehensive loss:
Unrealized (loss) gain on marketable securities, net of tax of $0	$ (4)	$ 14	$ (56)	$ 156
Foreign currency translation adjustments	87	(16)	159	(6)
Total other comprehensive income (loss)	83	(2)	103	150
Comprehensive loss	$ (14,755)	$ (12,873)	$ (27,294)	$ (25,760)