Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating expenses:
Research and development	$ 12,557	$ 10,058	$ 10,273
General and administrative	11,506	12,340	7,566
Total operating expenses	24,063	22,398	17,839
Operating loss	(24,063)	(22,398)	(17,839)
Other income (expense):
Interest income	187	60	5
Interest expense	(155)	(172)	(136)
Derivatives gain (loss)	593	(10,804)	(376)
Other income (expense), net	625	(10,916)	(507)
Net loss	$ (23,438)	$ (33,314)	$ (18,346)
Net loss per share, basic and diluted (in dollars per share)	$ (0.76)	$ (1.26)	$ (0.83)
Weighted average number of common shares outstanding, basic and diluted	31,025,585	26,461,374	22,080,761