Consolidated Statements of Convertible Preferred Shares and Shareholders’ Equity (Deficit) - USD ($) $ in Thousands	Series A Convertible Preferred Shares	Series B1 Convertible Preferred Shares	Series B2 Convertible Preferred Shares	Ordinary Shares	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Beginning balance at Dec. 31, 2016	$ 41,820
Beginning balance (in shares) at Dec. 31, 2016	2,800,001
Increase (decrease) in convertible preferred shares
Issuance of convertible preferred shares		$ 54,621
Issuance of convertible preferred shares (in shares)		3,947,198
Ending balance at Dec. 31, 2017	$ 41,820	$ 54,621
Ending balance (in shares) at Dec. 31, 2017	2,800,001	3,947,198
Beginning balance at Dec. 31, 2016				$ 4	$ 323	$ (2,286)	$ (31,837)	$ (33,796)
Beginning balance (in shares) at Dec. 31, 2016				316,215
Increase (decrease) in shareholders' equity (deficit)
Issuance of restricted share awards				$ 1	114			115
Issuance of restricted share awards (in shares)				48,480
Issuance of ordinary shares upon exercise of share options (in shares)				4,300
Share based compensation expense					401			401
Foreign currency translation adjustment						2,355		2,355
Net loss							(16,259)	(16,259)
Ending balance at Dec. 31, 2017				$ 5	838	69	(48,096)	(47,184)
Ending balance (in shares) at Dec. 31, 2017				368,995
Increase (decrease) in convertible preferred shares
Issuance of convertible preferred shares			$ 25,756
Issuance of convertible preferred shares (in shares)			1,323,248
Ending balance at Dec. 31, 2018	$ 41,820	$ 54,621	$ 25,756
Ending balance (in shares) at Dec. 31, 2018	2,800,001	3,947,198	1,323,248
Increase (decrease) in shareholders' equity (deficit)
Issuance of restricted share awards				$ 1	223			224
Issuance of restricted share awards (in shares)				95,644
Issuance of ordinary shares in exchange for surrender of vested share options				$ 4	(4)
Issuance of ordinary shares in exchange for surrender of vested share options (in shares)				340,728
Issuance of ordinary shares upon exercise of share options (in shares)				9,361
Share based compensation expense					800			800
Foreign currency translation adjustment						(1,820)		(1,820)
Net loss							(21,846)	(21,846)
Ending balance at Dec. 31, 2018				$ 10	1,857	(1,751)	(69,942)	$ (69,826)
Ending balance (in shares) at Dec. 31, 2018				814,728				814,728
Increase (decrease) in convertible preferred shares
Issuance of convertible preferred shares			$ 1,583
Issuance of convertible preferred shares (in shares)			80,385
Conversion of convertible preferred shares to ordinary shares	$ (41,820)	$ (54,621)	$ (27,339)
Conversion of convertible preferred shares to ordinary shares (in shares)	(2,800,001)	(3,947,198)	(1,403,633)
Ending balance (in shares) at Dec. 31, 2019	0	0	0
Increase (decrease) in shareholders' equity (deficit)
Conversion of convertible preferred shares to ordinary shares				$ 146	123,634			$ 123,780
Conversion of convertible preferred shares to ordinary shares (in shares)				11,647,529
Reclassification of warrant liability to additional paid-in capital and exercise of warrants				$ 9	10,018			10,027
Reclassification of warrant liability to additional paid-in capital and exercise of warrants (in shares)				723,992
Issuance of ADSs in initial public offering, net of underwriting discounts, commissions and offering expenses of $8.5 million				$ 59	56,322			56,381
Number of shares issued (in shares)				4,637,666
Issuance of restricted share awards				$ 2	395			397
Issuance of restricted share awards (in shares)				83,947
Issuance of ordinary shares upon exercise of share options				$ 1	142			143
Issuance of ordinary shares upon exercise of share options (in shares)				85,839
Share based compensation expense					2,688			2,688
Foreign currency translation adjustment						216		216
Net loss							(30,608)	(30,608)
Ending balance at Dec. 31, 2019				$ 227	$ 195,056	$ (1,535)	$ (100,550)	$ 93,198
Ending balance (in shares) at Dec. 31, 2019				17,993,701				17,993,701