Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Research contract revenue	$ 200	$ 200	$ 400	$ 400
Operating expenses:
Research and development, including costs of research contracts	8,346	14,775	14,888	33,887
General and administrative	3,031	3,721	6,473	8,392
Total operating expenses	11,377	18,496	21,361	42,279
Loss from operations	(11,177)	(18,296)	(20,961)	(41,879)
Other income (expense), net	1	7	(8)	3
Change in fair value of warrants	5,600	(403)	5,682	10,385
Net loss	$ (5,576)	$ (18,692)	$ (15,287)	$ (31,491)
Net loss per share - basic and diluted	$ (0.06)	$ (0.22)	$ (0.15)	$ (0.38)
Weighted average common shares outstanding to compute net loss per share - basic and diluted	100,422,564	83,082,633	100,326,416	82,994,845