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	$ (180,664)	$ (112,717)	$ (66,819)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	32,477	26,779	12,083
Depreciation and amortization	6,546	3,689	1,409
Non-cash interest	383	442	468
Deferred income tax provision (benefit)	3,306	(4,976)	(1,668)
Other non-cash charges	661
Changes in operating assets and liabilities:
Accounts receivable	2,482	(1,641)	4,543
Research and development incentives receivable	(3,684)	(9,707)	(1,866)
Prepaid expenses and other assets	(2,072)	(2,020)	(2,974)
Operating lease rightofuse assets	4,186	2,698	404
Accounts payable	8,002	2,561	1,196
Accrued expenses and other current liabilities	2,398	12,362	1,185
Operating lease liabilities	(4,109)	(2,114)	(582)
Deferred revenue	68,951	(2,135)	37,117
Other long-term liabilities	509	668	710
Net cash used in operating activities	(60,628)	(86,111)	(14,794)
Cash used in investing activities:
Purchases of property and equipment	(2,929)	(18,987)	(2,030)
Net cash used in investing activities	(2,929)	(18,987)	(2,030)
Cash flows from financing activities:
Proceeds from the issuance of ADSs and non-voting ordinary shares, net of issuance costs	249,345	5,703	290,984
Issuance of ordinary shares pursuant to the Ionis share purchase agreement			7,558
Proceeds from the exercise of share options and sale of ordinary shares	682	989	7,183
Proceeds from issuance of debt			15,000
Net cash provided by financing activities	250,027	6,692	320,725
Effect of exchange rate changes on cash, cash equivalents and restricted cash	1,346	(1,120)	(1,211)
Net increase (decrease) in cash, cash equivalents and restricted cash	187,816	(99,526)	302,690
Cash, cash equivalents and restricted cash at beginning of period	339,154	438,680	135,990
Cash, cash equivalents and restricted cash at end of period	526,970	339,154	438,680
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	526,423	339,154	438,680
Restricted cash included in other assets	547	0
Total cash, cash equivalents and restricted cash	526,970	339,154	438,680
Supplemental disclosure of cash flow information
Cash paid for interest	2,753	2,793	2,515
Cash paid for income taxes	562	2,228	73
Cash paid for amounts included in the measurement of operating lease liabilities	5,595	3,154	911
Changes in purchases of property and equipment in accounts payable and accrued expenses	(1,744)	1,564	324
Non-cash impact to right-of-use asset and operating lease liabilities	$ 3,898	$ 3,120	$ 13,846