Statements of Comprehensive Income (Loss) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenue
Collaborations, licenses and milestones	$ 4,340,000	$ 7,252,000
Operating expenses
Research and development	15,048,000	10,035,000
General and administrative	4,811,000	3,950,000
Total operating expenses	19,859,000	13,985,000
Loss from operations	(15,519,000)	(6,733,000)
Other income (expenses)
Interest income	1,057,000	359,000
Interest expense	(3,000)	(27,000)
Other income		3,000
Total other income, net	1,054,000	335,000
Loss before income tax	(14,465,000)	(6,398,000)
Income tax expense	170,000	0
Net loss	(14,635,000)	(6,398,000)
Other comprehensive loss
Net unrealized gain on marketable securities	245,000	619,000
Comprehensive loss	$ (14,390,000)	$ (5,779,000)
Net loss per share attributable to common shareholders:
Basic and diluted net loss (in dollars per share)	$ (0.31)	$ (0.16)
Weighted average shares used to compute net loss per share attributable to common stockholders:
Weighted-average common shares outstanding- basic and diluted (in shares)	46,598,797	40,626,729