Condensed Consolidated Statements of Operations (Unaudited) - 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	$ 8,420	$ 11,307	$ 17,624	$ 23,307
General and administrative	3,487	4,126	7,494	8,241
Total operating expenses	11,907	15,433	25,118	31,548
Loss from operations	(11,907)	(15,433)	(25,118)	(31,548)
Other income (expense), net	(231)	50	(425)	78
Net loss	$ (12,138)	$ (15,383)	$ (25,543)	$ (31,470)
Net loss per share, basic and diluted	$ (0.51)	$ (0.65)	$ (1.07)	$ (1.33)
Weighted average common shares outstanding, basic and diluted	23,810,112	23,672,527	23,774,736	23,655,366