Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues:
Collaboration agreements	$ 3,306	$ 3,711
Research grants	119	231
Total revenues	3,425	3,942
Operating expenses:
Research and development	12,942	15,266
General and administrative	7,275	5,357
Total operating expenses	20,217	20,623
Loss from operations	(16,792)	(16,681)
Interest and other income, net	160	187
Net loss	$ (16,632)	$ (16,494)
Basic and diluted net loss per share	$ (0.23)	$ (0.23)
Shares used in computing basic and diluted net loss per share	71,025	70,373