STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended			100 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011
Revenue	$ 667			$ 667
Operating expenses:
Research and development	57,083	12,910	4,556	128,899
General and administrative	14,984	11,636	7,567	68,795
Total operating expenses	72,067	24,546	12,123	197,694
Loss from operations	(71,400)	(24,546)	(12,123)	(197,027)
Other income, net	39	765	13	4,714
Change in fair value of warrants	7,583	(8,889)	4,461	4,721
Net loss	$ (63,778)	$ (32,670)	$ (7,649)	$ (187,592)
Basic and diluted net loss per share	$ (0.97)	$ (0.71)	$ (0.33)
Weighted average common shares outstanding used to compute basic and diluted net loss per share	66,003,789	46,003,996	23,108,039