Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash Flows From Operating Activities:
Net loss for the period	$ (34,941)	$ (34,757)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	6,062	4,755
Depreciation expense	441	516
Non-cash lease expense	541	544
Foreign exchange (gain) loss	66	(40)
Net (accretion)/amortization of marketable securities	(1,839)	21
Deferred tax	0	(1,315)
Changes in operating assets and liabilities:
Prepaid expenses	1,330	2,399
Research and development tax credits receivable	(379)	(399)
Collaboration revenue receivable	(2,528)	0
Other receivables	166	(5)
Other non-current assets	89	0
Accounts payable	2,016	(772)
Accrued expenses and other current liabilities	(4,203)	(1,487)
Operating lease liability, current portion	35	153
Income taxes payable	3,616	1,347
Operating lease liability, net of current portion	(581)	(558)
Deferred revenue	(1,677)	(408)
Net cash used in operating activities	(31,786)	(30,006)
Cash Flows From Investing Activities:
Purchases of property and equipment	(475)	(487)
Proceeds from maturities of marketable securities	92,500	2,650
Purchase of marketable securities	(98,711)	(1,760)
Net cash (used in) provided by investing activities	(6,686)	403
Cash Flows From Financing Activities:
Proceeds from exercise of stock options	4	28
Proceeds from issuance of common stock under the 2020 Employee Share Purchase Plan	409	213
Net cash provided by financing activities	413	241
Effect of exchange rate fluctuations on cash held	(1)	71
Net Decrease In Cash And Cash Equivalents	(38,060)	(29,291)
Cash and cash equivalents at beginning of period	159,521	334,427
Cash and cash equivalents at end of period	121,461	305,136
Supplemental Disclosure Of Cash Flow Information:
Property and equipment purchases incurred but not yet paid	1,134	1,541
Right-of-use asset obtained in exchange for new operating lease liability	$ 146	$ 56