Consolidated Statements of Operations and Comprehensive Loss - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenue	$ 1,626,029	$ 2,417,140	$ 4,581,622	$ 5,108,121
Operating expenses:
Research and development	2,945,096	4,918,961	6,162,768	10,665,890
General and administrative	2,231,817	2,933,982	4,298,299	5,381,917
Impairment charges				490,676
Total operating expenses	5,176,913	7,852,943	10,461,067	16,538,483
Loss from operations	(3,550,884)	(5,435,803)	(5,879,445)	(11,430,362)
Other income (expense):
Changes in fair value of warrant liability	(46,000)	(5,228,691)	(46,000)	(3,680,709)
Changes in fair value of embedded derivatives		4,912		(2,130)
Interest expense	(748)	(1,921)	(1,488)	(2,791)
Interest income	239,964	25,617	425,211	57,206
Other income (expense)	(29,220)	(49)	17,528	257,675
Total other income (expense)	163,996	(5,200,132)	395,251	(3,370,749)
Net loss before income tax benefit	(3,386,888)	(10,635,935)	(5,484,194)	(14,801,111)
Income tax benefit		1,497,093		2,488,731
Net loss	(3,386,888)	(9,138,842)	(5,484,194)	(12,312,380)
Other comprehensive income (loss) – foreign currency translation adjustments		(1,078,648)		(463,177)
Comprehensive loss	(3,386,888)	(10,217,490)	(5,484,194)	(12,775,557)
Net loss	(3,386,888)	(9,138,842)	(5,484,194)	(12,312,380)
Preferred stock accretion and other deemed dividends		(700,093)	(452,925)	(2,591,414)
Net loss attributed to common stockholders	$ (3,386,888)	$ (9,838,935)	$ (5,937,119)	$ (14,903,794)
Weighted-average common shares outstanding, basic and diluted	13,127,773	956,057	11,318,819	817,077
Net loss per share attributed to common stockholders, basic and diluted	$ (0.26)	$ (10.29)	$ (0.52)	$ (18.24)