Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (34,104)	$ (23,438)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	6,396	3,440
Depreciation and amortization	665	615
Non-cash interest	223
Changes in operating assets and liabilities:
Accounts receivable	5,544	(332)
Research and development incentives receivable	(4,982)	(4,446)
Prepaid expenses and other current assets	278	267
Operating lease right-of-use assets	(2,229)	374
Other assets	(554)	(292)
Accounts payable	2,225	1,325
Accrued expenses and other current liabilities	(603)	2,050
Operating lease liabilities	2,296	4
Deferred revenue	(1,549)	29,013
Other long-term liabilities	317	233
Net cash (used in) provided by operating activities	(26,077)	8,813
Cash used in investing activities:
Purchases of property and equipment	(794)	(621)
Net cash used in investing activities	(794)	(621)
Cash flows from financing activities:
Proceeds from the issuance of ADSs, net of issuance costs	72,752
Proceeds from the exercise of share options and sale of ordinary shares	1,859	11
Proceeds from issuance of debt	15,000
Proceeds from the exercise of warrants		1
Net cash provided by financing activities	89,611	12
Effect of exchange rate changes on cash	8	(3,411)
Net increase in cash	62,748	4,793
Cash at beginning of period	135,990	92,117
Cash at end of period	198,738	96,910
Supplemental disclosure of cash flow information
Cash paid for interest	1,074
Cash paid for income taxes	53	38
Public offering costs accrued but not paid		274
Cash paid for amounts included in the measurement of operating lease liabilities	200	406
Purchases of property and equipment included in accounts payable and accrued expenses	$ 36	$ 12