Statements of Operations and Comprehensive Loss (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating expenses:
Research and development expenses	$ 5,346,763	$ 2,871,239
General and administrative expenses	3,685,597	1,311,030
Total operating expenses	9,032,360	4,182,269
Loss from operations	(9,032,360)	(4,182,269)
Other income (expense):
Warrant remeasurement	0	(96,192)
Interest income	42,814	139
Interest expense	(180,864)	(190,163)
Net loss	(9,170,410)	(4,468,485)
Comprehensive loss	(9,170,410)	(4,468,485)
Cumulative dividend on Series C , C-1 and C-2 convertible preferred stock	0	(683,181)
Net loss attributable to common stockholders	$ (9,170,410)	$ (5,151,666)
Loss per share attributable to common stockholders basic and diluted (in dollars per share)	$ (0.32)	$ (3.05)
Weighted average common shares outstanding basic and diluted (in shares)	28,812,907	1,688,475