Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (48,782)	$ (33,577)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	9,084	4,950
Depreciation and amortization	1,002	944
Non-cash interest	347
Changes in operating assets and liabilities:
Accounts receivable	5,544	(2,685)
Research and development incentives receivable	1,318	937
Prepaid expenses and other current assets	(719)	(773)
Operating lease right-of-use assets	(2,024)	570
Other assets	(955)	(719)
Accounts payable	270	193
Accrued expenses and other current liabilities	(521)	1,030
Operating lease liabilities	2,123	(193)
Deferred revenue	28,473	27,782
Other long-term liabilities	481	369
Net cash used in operating activities	(4,359)	(1,172)
Cash used in investing activities:
Purchases of property and equipment	(963)	(716)
Net cash used in investing activities	(963)	(716)
Cash flows from financing activities:
Proceeds from the issuance of ADSs, net of issuance costs	102,595	46,373
Issuance of ordinary shares pursuant to the Ionis share purchase agreement	7,558
Proceeds from the exercise of share options	4,908	98
Proceeds from issuance of debt	15,000	15,000
Payments of debt issuance costs		(373)
Proceeds from the exercise of warrants		1
Net cash provided by financing activities	130,061	61,099
Effect of exchange rate changes on cash	(1,205)	(1,486)
Net increase in cash	123,534	57,725
Cash at beginning of period	135,990	92,117
Cash at end of period	259,524	149,842
Supplemental disclosure of cash flow information
Cash paid for interest	1,753
Cash paid for income taxes	87	124
Public offering costs accrued but not paid		50
Cash paid for amounts included in the measurement of operating lease liabilities	676	823
Purchases of property and equipment included in accounts payable and accrued expenses	$ 298	40
Debt issuance costs accrued but not paid		$ 200