Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (118,464)	$ (91,505)	$ (71,742)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	242	330	175
Non-cash interest	636	0	0
Loss on disposal of property and equipment	40	0	0
Non-cash (gain) loss on foreign currency remeasurement	(2,617)	1,141	22
Non-cash share-based compensation	17,277	13,123	8,639
Non-cash lease expenses	2,027	2,126	1,797
Changes in operating assets and liabilities
Prepaid expenses and other current assets	10,458	(28,760)	(8,984)
Deferred and prepaid tax assets	(1,661)	(1,701)	(877)
Long-term prepaid expenses and other assets	(5,842)	(307)	(160)
Operating lease liabilities	(1,959)	(2,081)	(1,880)
Accounts payable	864	2,497	(163)
Accrued expenses and other liabilities	1,623	(314)	5,428
Net cash used in operating activities	(97,376)	(105,451)	(67,745)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(66)	(596)	(334)
Proceeds from disposal of property and equipment	2	0	0
Net cash used in investing activities	(64)	(596)	(334)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of ordinary shares, net of issuance costs	144,935	440	154,794
Proceeds from the issuance of shares under the employee share purchase plan	351	199	0
Payments of withholding tax on stock award	(265)	0	0
Net proceeds from issuance of long-term debt	29,585	0	0
Payment of issuance cost of long-term debt	(778)	0	0
Proceeds from exercise of share options	2	401	1,852
Net cash provided by financing activities	173,830	1,040	156,646
Effect of exchange rate changes on cash, cash equivalents and restricted cash	867	(24,959)	(5,576)
Net increase/(decrease) in cash, cash equivalents and restricted cash	77,257	(129,966)	82,991
Cash, cash equivalents and restricted cash, beginning of the period	143,381	273,347	190,356
Cash, cash equivalents and restricted cash, end of the period	220,638	143,381	273,347
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid for interest	1,254	0	0
SUPPLEMENTAL NON-CASH TRANSACTIONS:
Right-of-use assets obtained in exchange for new operating lease liabilities	4,184	783	5,562
Unpaid withholding tax on stock award recognized in accrued and other liabilities	0	85	0
Proceeds from exercise of options received and recorded in other current assets	0	0	53
Deferred issuance costs included in accrued expenses	0	0	856
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	220,198	143,206	273,243
Short-term restricted cash	440	175	104
Total cash, cash equivalents and restricted cash	220,638	143,381	273,347
Long-term Debt Issuance
SUPPLEMENTAL NON-CASH TRANSACTIONS:
Issuance of warrants	687	0	0
Ordinary Shares Issuance
SUPPLEMENTAL NON-CASH TRANSACTIONS:
Issuance of warrants	$ 2,011	$ 0	$ 0