Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating expenses:
Research and development	$ 5,398	$ 6,436
General and administrative	2,363	2,770
Total operating expenses	7,761	9,206
Loss from operations	(7,761)	(9,206)
Other (expense) income:
Interest expense	(149)	(243)
Interest and investment income	39	53
Other expense, net	(5)	(22)
Total other expense, net	(115)	(212)
Net loss	$ (7,876)	$ (9,418)
Net loss per share - basic and diluted (in dollars per share)	$ (0.41)	$ (0.61)
Weighted-average common shares outstanding used in net loss per share - basic and diluted (in shares)	19,093,273	15,335,516