Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (112,717)	$ (66,819)	$ (51,010)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	26,779	12,083	6,514
Depreciation and amortization	3,689	1,409	1,277
Non-cash interest	442	468	78
Deferred income tax benefit	(4,976)	(1,668)	(673)
Changes in operating assets and liabilities:
Accounts receivable	(1,641)	4,543	(2,149)
Research and development incentives receivable	(9,707)	(1,866)	(1,786)
Prepaid expenses and other assets	(2,020)	(2,974)	502
Operating lease right-of-use assets	2,698	404	771
Accounts payable	2,561	1,196	(663)
Accrued expenses and other current liabilities	12,362	1,185	4,832
Operating lease liabilities	(2,114)	(582)	(621)
Deferred revenue	(2,135)	37,117	24,622
Other long-term liabilities	668	710	517
Net cash used in operating activities	(86,111)	(14,794)	(17,789)
Cash used in investing activities:
Purchases of property and equipment	(18,987)	(2,030)	(1,200)
Net cash used in investing activities	(18,987)	(2,030)	(1,200)
Cash flows from financing activities:
Proceeds from the issuance of ADSs, net of issuance costs	5,703	290,984	48,144
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	989	7,183	271
Proceeds from the exercise of warrants			1
Proceeds from issuance of debt		15,000	15,000
Payments of debt issuance costs			(573)
Net cash provided by financing activities	6,692	320,725	62,843
Effect of exchange rate changes on cash and cash equivalents	(1,120)	(1,211)	19
Net (decrease) increase in cash and cash equivalents	(99,526)	302,690	43,873
Cash and cash equivalents at beginning of period	438,680	135,990	92,117
Cash and cash equivalents at end of period	339,154	438,680	135,990
Supplemental disclosure of cash flow information
Cash paid for interest	2,793	2,515	378
Cash paid for income taxes	2,228	73	124
Cash paid for amounts included in the measurement of operating lease liabilities	3,154	911	961
Purchases of property and equipment included in accounts payable and accrued expenses	1,564	324	109
Advance billings on deferred revenue included in accounts receivable			$ 3,000
Non-cash impact right-of-use asset and operating lease liabilities	$ 3,120	$ 13,846