Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (11,324)	$ (6,503)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	2,121	276
Depreciation and amortization	305	213
Change in fair value of warrant liability	0	3,197
Changes in operating assets and liabilities:
Accounts receivable	(846)	4,860
Research and development incentives receivable	(2,097)	(1,650)
Prepaid expenses and other current assets	347	(215)
Operating lease right-of-use assets	187	176
Other assets	(215)	125
Accounts payable	2,702	415
Accrued expenses and other current liabilities	(464)	(783)
Lease liabilities	191	(176)
Deferred revenue	30,103	(5,327)
Other long-term liabilities	152	191
Net cash provided by (used in) operating activities	21,162	(5,201)
Cash used in investing activities:
Purchases of property and equipment	(320)	(418)
Net cash used in investing activities	(320)	(418)
Cash flows from financing activities:
Payments of initial public offering costs		(1,300)
Proceeds from the exercise of share options and sale of ordinary shares	2
Net cash provided by financing activities	2	34
Effect of exchange rate changes on cash	(3,324)	1,569
Net increase (decrease) in cash	17,520	(4,016)
Cash at beginning of period	92,117	63,380
Cash at end of period	109,637	59,364
Supplemental disclosure of cash flow information
Cash paid for income taxes	11
Cash paid for amounts included in the measurement of operating lease liabilities		224
Purchases of property and equipment included in accounts payable and accrued expenses	$ 71
Deferred initial public offering costs accrued but not paid		431
Series B2 Convertible Preferred Shares
Cash flows from financing activities:
Proceeds from issuance of convertible preferred shares, net of issuance costs		$ 1,334