CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
License revenue - related party	$ 4,209,576	$ 784,960
Operating expenses:
General and administrative	11,806,134	8,499,475
Research and development	8,083,342	12,976,229
Total operating expenses	19,889,476	21,475,704
Loss from operations	(15,679,900)	(20,690,744)
Other non-operating income (expense):
Foreign currency (loss) gain	(756,701)	2,718,400
Interest income	789,370
Interest expense	(33,966)	(9,574)
Net loss	(15,681,197)	(17,981,918)
Other comprehensive income (loss):
Foreign currency translation gain (loss)	3,945,924	(1,133,683)
Total comprehensive loss	$ (11,735,273)	$ (19,115,601)
Basic and diluted adjusted net loss per ordinary share	$ (0.43)	$ (0.62)
Weighted-average number of ordinary shares outstanding	36,624,950	28,776,915