Condensed Statements of Comprehensive Loss (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Product revenues		$ 95		$ 95
Operating expenses:
Research and development	2,240	1,165	5,798	2,514
General and administrative	1,213	1,577	4,207	3,764
Total operating expenses	3,453	2,742	10,005	6,278
Loss from operations	(3,453)	(2,647)	(10,005)	(6,183)
Investment income	2	1	4	3
Other (expense) income, net	1		(8)
Net loss and comprehensive loss	(3,450)	(2,646)	(10,009)	(6,180)
Non-cash deemed dividend to preferred stock		(2,318)		(4,799)
Net loss attributable to common stock	$ (3,450)	$ (4,964)	$ (10,009)	$ (10,979)
Basic and diluted net loss per share attributable to common stock	$ (0.17)	$ (1.88)	$ (0.64)	$ (4.84)
Weighted-average number of common shares outstanding	20,705	2,640	15,716	2,268