Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities:
Net loss	$ (125,373)	$ (78,882)	$ (28,837)
Items not involving cash:
Depreciation	1,624	906	644
Amortization of discount on term loan	0	0	216
Deferred income tax (recovery) expense	(44)	58	(285)
Stock-based compensation	20,376	10,017	5,677
Unrealized foreign exchange loss (gain)	2,729	327	(434)
Unrealized fair value loss (gain) on trading securities	2,934	719	(4)
Loss on repayment of term loan (note 11)	0	0	988
Changes in operating assets and liabilities:
Accounts receivable	1,757	(459)	(1,032)
Prepaid expenses and other current assets	(10,495)	(1,517)	(269)
Accounts payable and accrued expenses	8,062	2,971	2,022
Deferred revenue	0	(3,642)	(26,810)
Net cash used in operating activities	(98,430)	(69,502)	(48,124)
Investing activities:
Purchases of property, plant and equipment	(2,894)	(2,050)	(2,637)
Purchase of marketable securities	(551,137)	(389,474)	(228,897)
Proceeds from marketable securities	258,028	144,754	214,710
Net cash used in investing activities	(296,003)	(246,770)	(16,824)
Financing activities:
Repayment of term loan and repayment fees (note 11)	0	0	(16,743)
Issuance of common shares and pre-funded warrants, net of issuance costs (note 12a and note 12e)	277,766	447,283	102,456
Issuance of common shares pursuant to exercise of stock options	705	260	82
Net cash provided by financing activities	278,471	447,543	85,795
Effect of exchange rate changes on cash and cash equivalents	(2,484)	(592)	(593)
Increase in cash and cash equivalents	(118,446)	130,679	20,254
Cash and cash equivalents, beginning of year	175,688	45,009	24,755
Cash and cash equivalents, end of year	57,242	175,688	45,009
Supplemental disclosures:
Interest paid	0	0	339
Interest received	8,694	3,517	4,115
Cash paid for operating lease	919	824	634
Supplemental disclosures of non-cash transactions:
Fair value of stock options exercised on a cashless basis	4,491	3,349	887
Purchases of property, plant and equipment included in accounts payable and accrued expenses	391	0	0
Right-of-use asset obtained in exchange for new operating lease liability (note 9)	3,019	0	0
Increase in operating lease liability and accounts receivable related to lease incentives claimed in the period (note 9)	0	493	0
Increase in operating lease right-of-use asset and operating lease liability related to lease amendments (note 9)	$ 0	$ 5,248	$ 2,907