Consolidated Statements of Operations and Comprehensive (Loss) Income - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2017
Income Statement [Abstract]
License revenue		$ 7,724,001
Operating expenses
Research and development	(1,637,387)	(3,929,558)	(4,438,264)
General and administrative	(803,069)	(6,852,988)	(6,629,344)
Operating loss	(2,440,456)	(3,058,545)	(11,067,608)
Other income (loss)
Change in fair value of warrant liabilities	3,493,664		(5,411,551)
Realized and unrealized loss on available for sale marketable securities		(3,581,193)
Dividend income		85,242
Amortization of beneficial conversion feature and debt issuance costs related to convertible note			(1,031,360)
Issuance cost related to warrants to investors and placement agent			(457,250)
Imputed interest with respect to convertible notes			(14,878)
Amortization of debt issuance cost			(14,273)
Foreign exchange loss	(5,521)	(920)
Issuance of common stock to finder fee upon the conversion of convertible notes			(18,000)
Other expenses		(3,034)	(29,426)
Total other income (loss)	3,488,143	(3,499,905)	(6,976,738)
Provision for income taxes
Net (loss) income	1,047,687	(6,558,450)	(18,044,346)
Unrealized income (loss) on marketable securities	(5,135)		2,149
Total other comprehensive (loss) income	$ 1,042,552	$ (6,558,450)	$ (18,042,197)
Net (loss) income (loss) per share - basic	$ 0.15	$ (0.77)	$ (3.01)
Net (loss) income per share - diluted	$ 0.14	$ (0.77)	$ (3.01)
Weighted average number of common shares outstanding - basic	7,196,048	8,498,525	6,002,052
Weighted average number of common shares outstanding - diluted	7,250,194	8,498,525	6,002,052