CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue from related party		$ 469		$ 946
Total revenues	$ 21,338	8,752	$ 35,522	20,405
Operating expenses:
Research and development	25,553	28,076	48,011	42,652
General and administrative	9,042	6,049	16,398	11,740
Total operating expenses	34,595	34,125	64,409	54,392
Loss from operations	(13,257)	(25,373)	(28,887)	(33,987)
Interest income	1,540	357	2,915	594
Other income (expense), net	61	(174)	(79)	(54)
Loss before provision for income taxes	(11,656)	(25,190)	(26,051)	(33,447)
Provision for income taxes	1,791	26	2,889	26
Net loss	$ (13,447)	$ (25,216)	$ (28,940)	$ (33,473)
Net loss per share, basic and diluted	$ (0.35)	$ (0.69)	$ (0.75)	$ (0.91)
Shares used to compute net loss per share, basic and diluted	38,961,021	36,780,897	38,805,317	36,660,548
Other comprehensive loss:
Changes in unrealized gains (losses) on short-term investments	$ 50	$ (10)	$ (84)	$ (83)
Comprehensive loss	(13,397)	(25,226)	(29,024)	(33,556)
License and Service
Revenues	$ 21,338	$ 8,283	$ 35,522	$ 19,459