Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue:
Collaboration and license revenue	$ 9,623	$ 883	$ 18,861	$ 883
Grant revenue	260	102	596	127
Total revenue	9,883	985	19,457	1,010
Operating expenses:
Research and development	13,533	5,403	24,179	10,132
General and administrative	5,882	2,134	12,092	3,518
Total operating expenses	19,415	7,537	36,271	13,650
Loss from operations	(9,532)	(6,552)	(16,814)	(12,640)
(Loss) Gain from remeasurement of fair value of warrants	(16,735)	25	(26,077)	(125)
Gain on extinguishment of convertible promissory notes		3,553		3,553
Interest expense		(996)		(2,350)
Other income, net	7	344	15	152
Net loss	$ (26,260)	$ (3,626)	$ (42,876)	$ (11,410)
Net loss per common share, basic and diluted	$ (0.50)	$ (12.27)	$ (1.61)	$ (38.61)
Weighted average common shares outstanding, basic and diluted	52,653,344	295,498	26,678,848	295,498