Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Licensing revenue	$ 500,000	$ 500,000
Operating expenses:
Research and development	13,078,710	14,623,068
General and administrative	5,889,722	6,526,752
Total operating expenses	18,968,432	21,149,820
Loss from operations	(18,468,432)	(20,649,820)
Other income (expense):
Gain from change in earn-out milestone liability	649,701	733,186
Impairment of in-process research and development	(2,520,000)	(1,444,023)
Investment income, net	26,041	26,922
Interest expense	(91,756)	(722,993)
Other income (expense)	2,270	3,002
Total other expense	(1,933,744)	(1,403,906)
Net loss	(20,402,176)	(22,053,726)
Deemed dividend related to warrant modification	(345,685)
Net loss attributable to common shareholders	$ (20,747,861)	$ (22,053,726)
Net loss attributable to common shareholders per common share – basic and diluted (in dollars per share)	$ (2.72)	$ (11.89)
Weighted average common shares outstanding – basic and diluted (in shares)	7,627,210	1,854,054