Condensed Statements of Operations and Comprehensive Income (Loss) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenue:
Licensing revenue	$ 6,507	$ 1,989	$ 9,743	$ 3,978
Collaborative development revenue	2,630	5,302	7,944	9,869
Total revenue	9,137	7,291	17,687	13,847
Operating expenses:
Research and development	5,183	7,234	12,820	13,173
General and administrative	1,203	908	2,580	1,935
Total operating expenses	6,386	8,142	15,400	15,108
Income (loss) from operations	2,751	(851)	2,287	(1,261)
Other expense, net	(8)	(4)	(12)	(29)
Change in fair value of preferred stock warrant liability	1,010		(1,593)
Income (loss) before provision for income taxes	3,753	(855)	682	(1,290)
Provision for income taxes		36		71
Net income (loss) and comprehensive income (loss)	3,753	(891)	682	(1,361)
Net income (loss) attributable to common stockholders:
Basic	515	(891)		(1,361)
Diluted	$ 703	$ (891)		$ (1,361)
Shares used to compute net income (loss) per share attributable to common stockholders:
Basic	2,611,259	1,102,093	1,937,509	1,072,583
Diluted	3,904,136	1,102,093	1,937,509	1,072,583
Net income (loss) per share attributable to common stockholders:
Basic	$ 0.20	$ (0.81)		$ (1.27)
Diluted	$ 0.18	$ (0.81)		$ (1.27)