STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Collaboration revenue	$ 1,598	$ 1,869	$ 5,264	$ 2,413
Operating expenses:
Research and development, including costs of contracts	8,975	16,970	148,402	98,643
General and administrative	3,537	3,065	11,058	14,388
Total operating expenses	12,512	20,035	159,460	113,031
Loss from operations	(10,914)	(18,166)	(154,196)	(110,618)
Other income (expense), net	39	(4)	102	6
Change in derivative liabilities	21		21
Net loss	(10,854)	(18,170)	(154,073)	(110,612)
Preferred stock dividends	(3,591)		(3,591)
Net loss applicable to common stockholders	$ (14,445)	$ (18,170)	$ (157,664)	$ (110,612)
Net loss per common share - basic and diluted	$ (0.11)	$ (0.14)	$ (1.21)	$ (0.89)
Weighted average common shares outstanding used to compute net loss per share - basic and diluted	130,496,035	129,732,356	130,347,370	123,911,796