Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Collaboration agreements	$ 12,551	$ 3,306
Research grants	86	119
Total revenues	12,637	3,425
Operating expenses:
Research and development	23,547	12,942
General and administrative	10,087	7,275
Total operating expenses	33,634	20,217
Loss from operations	(20,997)	(16,792)
Interest and other income, net	810	160
Net loss	$ (20,187)	$ (16,632)
Basic and diluted net loss per share	$ (0.23)	$ (0.23)
Shares used in computing basic and diluted net loss per share	86,334	71,025