Unaudited Condensed Statements of Comprehensive Loss (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Expenses:
Research and development	$ 948	$ 474	$ 2,303	$ 844
General and administrative	3,225	2,974	9,238	6,485
Total expenses	4,173	3,448	11,541	7,329
Loss from operations	(4,173)	(3,448)	(11,541)	(7,329)
Other income (expense):
Adjustments to fair value of derivative liabilities	0	1,227	0	2,696
Other income (expense), net	1	(1)	3	1
Net loss	(4,172)	(2,222)	(11,538)	(4,632)
Preferred stock dividends	(337)	(205)	(801)	(281)
Net loss attributable to common stockholders	$ (4,509)	$ (2,427)	$ (12,339)	$ (4,913)
Net loss per share basic and diluted	$ (0.11)	$ (0.18)	$ (0.43)	$ (0.55)
Shares used in computing basic and diluted net loss per share	41,374	13,253	28,891	8,995