CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Expenses:
Research and development	$ 7,232	$ 2,817	$ 11,159	$ 6,390
General and administrative	2,338	1,691	4,526	3,503
Loss from operations	(9,570)	(4,508)	(15,685)	(9,893)
Interest income	65	31	181	71
Interest expense		(72)		(156)
Other income (expense)	1	(3)		(12)
Net loss	$ (9,504)	$ (4,552)	$ (15,504)	$ (9,990)
Per share information:
Net loss per share of common stock-basic and diluted (in dollars per share)	$ (0.24)	$ (0.21)	$ (0.38)	$ (0.47)
Basic and diluted weighted average shares outstanding (in shares)	40,395,650	21,985,213	40,384,429	21,288,545
Net loss	$ (9,504)	$ (4,552)	$ (15,504)	$ (9,990)
Other comprehensive loss:
Unrealized gain on available-for-sale securities	38		27
Total comprehensive loss	$ (9,466)		$ (15,477)