Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues:
Collaboration revenue	$ 930	$ 2,031	$ 1,401	$ 4,404
Grant revenue	101	1,007	249	2,132
Service and license revenue	519	10	527	10
Total revenues	1,550	3,048	2,177	6,546
Operating expenses:
Research and development	19,686	23,639	41,906	36,870
General and administrative	5,098	4,085	9,957	8,242
Unoccupied facility expense		178		255
Total operating expenses	24,784	27,902	51,863	45,367
Loss from operations	(23,234)	(24,854)	(49,686)	(38,821)
Other income (expense):
Interest income	18	55	45	120
Interest expense	(263)		(510)
Other (loss) income, net	(112)	22	343	84
Net loss	$ (23,591)	$ (24,777)	$ (49,808)	$ (38,617)
Basic and diluted net loss per share	$ (0.80)	$ (0.94)	$ (1.70)	$ (1.47)
Weighted average shares used to compute basic and diluted net loss per share	29,335	26,286	29,230	26,286