CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Expenses:
Research and development	$ 9,148	$ 2,642	$ 20,307	$ 9,032
General and administrative	2,073	1,571	6,599	5,074
Loss from operations	(11,221)	(4,213)	(26,906)	(14,106)
Interest income	111	45	292	116
Interest expense		(3)		(159)
Other income (expense)		1		(11)
Net loss	$ (11,110)	$ (4,170)	$ (26,614)	$ (14,160)
Per share information:
Net loss per share of common stock-basic and diluted (in dollars per share)	$ (0.27)	$ (0.15)	$ (0.66)	$ (0.60)
Basic and diluted weighted average shares outstanding (in shares)	40,407,146	28,666,656	40,392,084	23,531,745
Net loss	$ (11,110)	$ (4,170)	$ (26,614)	$ (14,160)
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale securities	42	(18)	68	(18)
Total comprehensive loss	$ (11,068)	$ (4,188)	$ (26,546)	$ (14,178)