Statements of Operations - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating expenses:
Research and development	$ 7,162,541	$ 4,602,513	$ 18,708,447	$ 8,387,693
General and administrative	1,802,660	1,446,371	5,215,169	3,603,528
Total operating expenses	8,965,201	6,048,884	23,923,616	11,991,221
Loss from operations	(8,965,201)	(6,048,884)	(23,923,616)	(11,991,221)
Other income (expense)
Interest expense	(551,713)	(392,009)	(1,525,136)	(1,173,723)
Interest income	1,175	1,288	3,682	1,425
Change in fair value of warrants	104,298	86,243	44,801	278,564
Loss on extinguishment of debt			1,035,981
Loss before benefit from income taxes	(9,411,441)	(6,353,362)	(26,436,250)	(12,884,955)
Benefit from income taxes				3,652,485
Net loss	$ (9,411,441)	$ (6,353,362)	$ (26,436,250)	$ (9,232,470)
Net loss per share - basic and diluted	$ (0.42)	$ (0.34)	$ (1.21)	$ (1.03)
Weighted-average shares outstanding - basic and diluted	22,272,777	18,592,968	21,923,070	8,967,324