Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Grant	$ 5,205	$ 4,628	$ 6,085
Operating expenses:
Research and development	22,815	18,143	11,453
General and administrative	10,066	8,391	5,947
Total operating expenses	32,881	26,534	17,400
Loss from operations	(27,676)	(21,906)	(11,315)
Other income (expense):
Interest income	482	244	22
Other expense, net	(42)	(36)	(2)
Total other income	440	208	20
Net loss	$ (27,236)	$ (21,698)	(11,295)
Deemed dividend to convertible preferred stockholders			$ (228)
Net loss per share, basic and diluted	$ (1.80)	$ (2.22)	$ (19.21)
Net loss attributable to common stockholders	$ (27,236)	$ (21,698)	$ (11,523)
Weighted-average common shares outstanding, basic and diluted	15,128,192	9,791,728	599,788