STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Research contract revenue	$ 633	$ 200	$ 1,033	$ 600
Operating expenses:
Research and development, including costs of research contracts	9,733	6,247	24,621	40,133
General and administrative	2,842	3,068	9,315	11,459
Total operating expenses	12,575	9,315	33,936	51,592
Loss from operations	(11,942)	(9,115)	(32,903)	(50,992)
Other income (expense), net	2	(191)	(6)	(190)
Change in fair value of warrants	5,847	(7,407)	11,529	2,979
Net loss	$ (6,093)	$ (16,713)	$ (21,380)	$ (48,203)
Net loss per share - basic and diluted	$ (0.06)	$ (0.20)	$ (0.21)	$ (0.58)
Weighted average common shares outstanding to compute net loss per share - basic and diluted	100,428,520	83,161,927	100,360,825	83,051,151