STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		103 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012
Collaboration revenue	$ 200	$ 67	$ 867
Operating expenses:
Research and development	13,985	24,641	142,884
General and administrative	4,848	3,352	73,643
Total operating expenses	18,833	27,993	216,527
Loss from operations	(18,633)	(27,926)	(215,660)
Other income (expense), net	(26)	(2)	4,688
Change in fair value of warrants	(5,811)	(11,080)	(1,090)
Net loss	$ (24,470)	$ (39,008)	$ (212,062)
Net loss per share - basic and diluted	$ (0.32)	$ (0.65)
Weighted average common shares outstanding used to compute net loss per share - basic and diluted	75,620,130	60,412,689