Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Consolidated Statements of Operations
Revenue		$ 250		$ 250
Operating expenses:
Research and development	$ 3,897	4,776	$ 13,383	14,693
General and administrative	2,111	2,426	6,900	7,189
Total operating expenses	6,008	7,202	20,283	21,882
Loss from operations	(6,008)	(6,952)	(20,283)	(21,632)
Other income (expense):
Interest expense	(10)	(105)	(100)	(381)
Interest and investment income	177	45	252	128
Other income (loss), net	162	(5)	321	18
Total other income (expense), net	329	(65)	473	(235)
Net loss	$ (5,679)	$ (7,017)	$ (19,810)	$ (21,867)
Net loss per share - basic and diluted (in dollars per share)	$ (0.08)	$ (0.31)	$ (0.45)	$ (1.03)
Weighted-average common shares outstanding used in net loss per share - basic and diluted (in shares)	71,038,419	22,563,174	43,603,950	21,163,591