Condensed Statements of Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating expenses:
Research and development	$ 1,981	$ 2,171	$ 3,650	$ 3,558
General and administrative	1,347	1,753	2,455	2,994
Total operating expenses	3,328	3,924	6,105	6,552
Loss from operations	(3,328)	(3,924)	(6,105)	(6,552)
Investment income	5	1	8	2
Other (expense) income, net	(1)	(6)	1	(9)
Net loss and comprehensive loss	$ (3,324)	$ (3,929)	$ (6,096)	$ (6,559)
Basic and diluted net loss per share attributable to common stock	$ (0.13)	$ (0.23)	$ (0.26)	$ (0.50)
Weighted-average number of common shares outstanding	26,545	17,259	23,835	13,179