Statements of Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Operating expenses:
Research and development	$ 8,764	$ 9,086
General and administrative	4,995	4,596
Total operating expenses	13,759	13,682
Loss from operations	(13,759)	(13,682)
Interest income	106	27
Other income (expense)	(1)	1
Net loss and comprehensive loss	$ (13,654)	$ (13,654)
Basic and diluted net loss per share attributable to common stock	$ (0.51)	$ (0.54)
Weighted-average number of common shares outstanding	26,545	25,201