Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenue
Collaborations, licenses and milestones	$ 7,090	$ 7,821	$ 24,771	$ 81,080
Operating expenses
Research and development	19,408	14,069	51,376	38,512
General and administrative	4,172	3,007	13,074	10,000
Total operating expenses	23,580	17,076	64,450	48,512
Income (loss) from operations	(16,490)	(9,255)	(39,679)	32,568
Other income (expenses)
Interest income	1,048	579	3,142	1,306
Interest expense	(3)	(2)	(8)	(39)
Other income	56	3	86	5
Total other income, net	1,101	580	3,220	1,272
Income (loss) before income taxes	(15,389)	(8,675)	(36,459)	33,840
Income tax expense (benefit)	173	(598)	623	1,150
Net income (loss)	(15,562)	(8,077)	(37,082)	32,690
Other comprehensive income (loss)
Net unrealized gain (loss) on marketable securities	143	(466)	344	266
Comprehensive income (loss)	$ (15,419)	$ (8,543)	$ (36,738)	$ 32,956
Net income (loss) per share attributable to common shareholders:
Basic net income (loss) (in dollars per share)	$ (0.33)	$ (0.20)	$ (0.79)	$ 0.80
Diluted net income (loss) (in dollars per share)	$ (0.33)	$ (0.20)	$ (0.79)	$ 0.78
Weighted average shares used to compute net income (loss) per share attributable to common stockholders:
Basic (in shares)	46,929,498	41,033,973	46,766,562	40,814,587
Diluted (in shares)	46,929,498	41,033,973	46,766,562	41,861,361