Condensed 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	$ 10,475	$ 9,235	$ 16,252	$ 14,116
General and administrative	3,520	1,830	6,265	3,783
Total operating expenses	13,995	11,065	22,517	17,899
Other income, net (Note 6)	229	164	435	287
Net loss	$ (13,766)	$ (10,901)	$ (22,082)	$ (17,612)
Net loss per common stock - basic and diluted (Note 7)	$ (0.59)	$ (0.63)	$ (0.94)	$ (1.02)
Basic and diluted weighted average number of common stock outstanding	23,444,150	17,212,007	23,433,708	17,211,997
Comprehensive loss:
Net loss	$ (13,766)	$ (10,901)	$ (22,082)	$ (17,612)
Other comprehensive income (loss) - unrealized gain (loss) on available-for-sale securities		119	(36)	362
Comprehensive loss	$ (13,766)	$ (10,782)	$ (22,118)	$ (17,250)