Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Collaboration and license revenue	$ 11,435
Grant revenue	500
Total revenue	11,935
Operating expenses:
Research and development	37,945	$ 33,183	$ 33,815
General and administrative	14,710	14,506	13,584
Total operating expenses	52,655	47,689	47,399
Loss from operations	(40,720)	(47,689)	(47,399)
Other income (expense):
Interest income	757	384	494
Interest expense			(24)
Total other income, net	757	384	470
Net loss	$ (39,963)	$ (47,305)	$ (46,929)
Basic and diluted net loss per common share	$ (0.86)	$ (1.08)	$ (1.08)
Shares used to compute basic and diluted net loss per common share	46,432	43,890	43,275