Condensed Statements of Comprehensive Loss (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Operating expenses:
Research and development	$ 2,171	$ 603	$ 3,558	$ 1,349
General and administrative	1,753	1,052	2,994	2,187
Total operating expenses	3,924	1,655	6,552	3,536
Loss from operations	(3,924)	(1,655)	(6,552)	(3,536)
Investment income	1	1	2	2
Other (expense) income, net	(6)		(9)
Net loss and comprehensive loss	(3,929)	(1,654)	(6,559)	(3,534)
Non-cash deemed dividend to preferred stock		(2,481)		(2,481)
Net loss attributable to common stock	$ (3,929)	$ (4,135)	$ (6,559)	$ (6,015)
Basic and diluted net loss per share attributable to common stock	$ (0.23)	$ (1.86)	$ (0.50)	$ (2.89)
Weighted-average number of common shares outstanding	17,259	2,227	13,179	2,082