Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
License and milestone fees	$ 530		$ 1,710
Collaborative revenue	313		2,093
Clinical compound revenue	68	$ 86
Total revenue	911	86	3,803
Operating expenses:
Research and development	48,524	49,253	21,221
General and administrative	11,872	9,233	7,770
Total operating expenses	60,396	58,486	28,991
Operating loss	(59,485)	(58,400)	(25,188)
Other income	1,156	652	101
Loss before benefit from income taxes	(58,329)	(57,748)	(25,087)
Benefit from income taxes	204	468	397
Net loss	$ (58,125)	$ (57,280)	$ (24,690)
Net loss per share:
Basic and Diluted	$ (1.86)	$ (2.10)	$ (1.00)
Weighted average shares:
Basic and Diluted	31,202,842	27,279,008	24,620,372
Other comprehensive income (loss), net of tax of $0:
Change in unrealized gains (losses) on available for sale marketable securities	$ (73)	$ 38	$ (35)
Total comprehensive loss	$ (58,198)	$ (57,242)	$ (24,725)