Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Operating expenses:
Research and development	$ 15,325	$ 13,114
General and administrative	6,156	6,965
Total operating expenses	21,481	20,079
Total operating loss	(21,481)	(20,079)
Other income (expense):
Interest income	45	52
Total other income (expense)	45	52
Net loss	(21,436)	(20,027)
Preferred stock dividends	(741)	(868)
Preferred stock accretion	(173)	(229)
Net loss applicable to common stockholders	$ (22,350)	$ (21,124)
Basic and diluted net loss per share	$ (0.76)	$ (0.88)
Shares used in computing basic and diluted net loss per share	29,216	24,120