Condensed Consolidated Statements of Operations - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
License revenue	$ 38,096	$ 38,096	$ 114,286	$ 114,286
Research and development:
Noncash stock expense associated with in-licensing agreements	0	4,138,844	0	5,350,094
Noncash compensation	35,756	1,200,575	2,733,110	6,402,296
Other research and development	11,538,246	8,352,154	29,719,891	13,197,183
Total research and development	11,574,002	13,691,573	32,453,001	24,949,573
General and administrative:
Noncash compensation	1,204,278	2,895,997	10,106,938	9,664,560
Other general and administrative	1,085,400	889,872	3,094,362	2,500,121
Total general and administrative	2,289,678	3,785,869	13,201,300	12,164,681
Total costs and expenses	13,863,680	17,477,442	45,654,301	37,114,254
Operating loss	(13,825,584)	(17,439,346)	(45,540,015)	(36,999,968)
Other (income) expense:
Interest income	(55,977)	(12,107)	(109,660)	(38,308)
Other income	0	0	0	(95,427)
Interest expense	246,527	234,787	730,710	695,914
Change in fair value of notes payable	(360,218)	(210,857)	(824,231)	(577,299)
Total other (income) expense	(169,668)	11,823	(203,181)	(15,120)
Net loss	$ (13,655,916)	$ (17,451,169)	$ (45,336,834)	$ (36,984,848)
Basic and diluted net loss per common share (in dollars per share)	$ (0.28)	$ (0.51)	$ (1.01)	$ (1.14)
Weighted average shares used in computing basic and diluted net loss per common share (in shares)	47,946,309	34,188,108	44,810,352	32,436,420