Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Operating expenses:
Research and development	$ 3,211	$ 2,795	$ 6,595	$ 5,364
General and administrative	3,715	2,991	7,000	5,990
Total operating expenses	6,926	5,786	13,595	11,354
Operating loss	(6,926)	(5,786)	(13,595)	(11,354)
Other income (expense):
Interest income	52	36	109	91
Interest expense	(20)	(29)	(40)	(92)
Derivatives gain (loss)	554	595	795	(452)
Other income (expense), net	586	602	864	(453)
Net loss	$ (6,340)	$ (5,184)	$ (12,731)	$ (11,807)
Net loss per share, basic and diluted (in dollars per share)	$ (0.20)	$ (0.16)	$ (0.40)	$ (0.39)
Weighted average number of common shares outstanding, basic and diluted	32,185,607	31,907,747	32,115,238	30,039,677
Other comprehensive loss:
Net loss	$ (6,340)	$ (5,184)	$ (12,731)	$ (11,807)
Other comprehensive loss:
Unrealized gain (loss) on marketable securities	1		(1)
Comprehensive loss	$ (6,339)	$ (5,184)	$ (12,732)	$ (11,807)