Fusion Pharmaceuticals (FUSN) 10-Q 9 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 02, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Trading Symbol	FUSN
Entity Registrant Name	Fusion Pharmaceuticals Inc.
Entity Central Index Key	0001805890
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		43,066,219
Entity Tax Identification Number	00-0000000
Entity File Number	001-39344
Entity Address, Address Line One	270 Longwood Rd., S.
Entity Address, City or Town	Hamilton
Entity Address, State or Province	ON
Entity Address, Country	CA
Entity Address, Postal Zip Code	L8P 0A6
City Area Code	289
Local Phone Number	799-0891
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	CA
Title of 12(b) Security	Common shares, no par value per share
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 38,379	$ 90,517
Accounts receivable	300
Short-term investments	154,238	131,882
Prepaid expenses and other current assets	9,423	5,340
Restricted cash	669	425
Total current assets	203,009	228,164
Property and equipment, net	2,460	1,967
Deferred tax assets	1,324	653
Restricted cash	1,222	1,466
Long-term investments	45,554	77,082
Operating lease right-of-use assets	6,946
Other non-current assets	7,788	1,344
Total assets	268,303	310,676
Current liabilities:
Accounts payable	3,803	3,399
Accrued expenses	6,146	4,659
Income taxes payable		2,799
Deferred revenue	2,287	1,000
Operating lease liabilities	1,327
Total current liabilities	13,563	11,857
Deferred rent, net of current portion		11
Income taxes payable, net of current portion	295	295
Deferred revenue, net of current portion	2,167	4,000
Operating lease liabilities, net of current portion	5,783
Total liabilities	21,808	16,163
Commitments and contingencies (Note 14)
Shareholders’ equity:
Common shares, no par value, unlimited shares authorized as of September 30, 2021 and December 31, 2020; 43,066,219 and 41,725,797 shares issued and outstanding as of September 30, 2021 and December 31, 2020, respectively
Additional paid-in capital	423,446	407,672
Accumulated other comprehensive income	63	44
Accumulated deficit	(177,014)	(113,203)
Total shareholders’ equity	246,495	294,513
Total liabilities and shareholders’ equity	$ 268,303	$ 310,676

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Common stock, no par value
Common stock, shares issued	43,066,219	41,725,797
Common stock, shares outstanding	43,066,219	41,725,797

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Total revenue	$ 325		$ 846
Type of Revenue [Extensible List]	us-gaap:CollaborativeArrangementMember	us-gaap:CollaborativeArrangementMember	us-gaap:CollaborativeArrangementMember	us-gaap:CollaborativeArrangementMember
Operating expenses:
Research and development	$ 12,684	$ 4,529	$ 44,546	$ 12,231
General and administrative	7,156	5,790	20,762	14,105
Total operating expenses	19,840	10,319	65,308	26,336
Loss from operations	(19,515)	(10,319)	(64,462)	(26,336)
Other income (expense):
Change in fair value of preferred share tranche right liability				(32,722)
Change in fair value of preferred share warrant liability				(6,399)
Interest income (expense), net	107	80	300	249
Refundable investment tax credits		41		139
Other income (expense), net	27	20	406	148
Total other income (expense), net	134	141	706	(38,585)
Loss before (provision) benefit for income taxes	(19,381)	(10,178)	(63,756)	(64,921)
Income tax (provision) benefit	(48)	185	(55)	(27)
Net loss	(19,429)	(9,993)	(63,811)	(64,948)
Unrealized (loss) gain on investments	(274)	(1)	19	(1)
Comprehensive loss	(19,703)	(9,994)	(63,792)	(64,949)
Reconciliation of net loss to net loss attributable to common shareholders:
Net loss	(19,429)	(9,993)	(63,811)	(64,948)
Dividends paid to preferred shareholders in the form of warrants issued				(1,382)
Net loss attributable to common shareholders	$ (19,429)	$ (9,993)	$ (63,811)	$ (66,330)
Net loss per share attributable to common shareholders—basic and diluted	$ (0.45)	$ (0.24)	$ (1.50)	$ (4.30)
Weighted-average common shares outstanding—basic and diluted	43,022,762	41,682,797	42,441,091	15,422,375

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Non-Controlling Interest, Convertible Preferred Shares and Shareholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Asset purchase agreements [Member]	Class B Convertible Preferred Shares And Class B Preferred Exchangeable Shares	Non-Controlling Interest in Fusion Pharmaceuticals (Ireland) Limited [Member]	Non-Controlling Interest in Fusion Pharmaceuticals (Ireland) Limited [Member]Class B Preferred Exchangeable Shares and Class B Preferred Share Tranche Right [Member]	Class A and B Convertible Preferred Shares [Member]	Class A and B Convertible Preferred Shares [Member]Class B Convertible Preferred Shares And Class B Preferred Share Tranche Right	Common Shares [Member]	Common Shares [Member]Asset purchase agreements [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Asset purchase agreements [Member]	Additional Paid-in Capital [Member]Class B Convertible Preferred Shares And Class B Preferred Exchangeable Shares	Accumulated Deficit [Member]	Accumulated Deficit [Member]Class B Convertible Preferred Shares And Class B Preferred Exchangeable Shares	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2019	$ (33,488)			$ 20,961		$ 71,592				$ 1,286			$ (34,774)
Beginning Balance (in shares) at Dec. 31, 2019						73,125,790		1,929,555
Issuance of Class B convertible/exchangeable preferred shares and Class B preferred share tranche right, net of issuance costs							$ 9,907
Issuance of Class B convertible/exchangeable preferred shares and Class B preferred share tranche right, net of issuance costs (in shares)							6,598,917
Initial fair value of Class B convertible preferred share tranche right liability						$ (1,105)
Issuance of warrants to purchase Class B convertible preferred shares and Class B preferred exchangeable shares as a non-cash dividend to preferred shareholders			$ (1,382)									$ (1,286)		$ (96)
Share-based compensation expense	358									358
Net loss	(10,222)												(10,222)
Ending Balance at Mar. 31, 2020	(44,734)			20,961		$ 80,394				358			(45,092)
Ending Balance (in shares) at Mar. 31, 2020						79,724,707		1,929,555
Beginning Balance at Dec. 31, 2019	(33,488)			20,961		$ 71,592				1,286			(34,774)
Beginning Balance (in shares) at Dec. 31, 2019						73,125,790		1,929,555
Unrealized (loss) gain on investments	(1)
Net loss	(64,948)
Ending Balance at Sep. 30, 2020	306,454									406,273			(99,818)		$ (1)
Ending Balance (in shares) at Sep. 30, 2020								41,702,384,000
Beginning Balance at Mar. 31, 2020	(44,734)			20,961		$ 80,394				358			(45,092)
Beginning Balance (in shares) at Mar. 31, 2020						79,724,707		1,929,555
Issuance of Class B convertible/exchangeable preferred shares and Class B preferred share tranche right, net of issuance costs					$ 6,722		$ 55,769
Issuance of Class B convertible/exchangeable preferred shares and Class B preferred share tranche right, net of issuance costs (in shares)							36,806,039
Reclassification of Class B convertible preferred share and preferred exchangeable share tranche right liability upon settlement				4,257		$ 35,311
Conversion of Class A and B preferred exchangeable shares into Class A and B convertible preferred shares				$ (31,940)		$ 31,940
Conversion of Class A and B preferred exchangeable shares into Class A and B convertible preferred shares (in shares)						28,874,378
Conversion of Class A and B convertible preferred shares into common shares	203,414					$ (203,414)				203,414
Conversion of Class A and B convertible preferred shares into common shares (in shares)						(145,405,124)		27,234,489
Conversion of convertible preferred share warrants into common share warrants	7,781									7,781
Issuance of common shares upon closing of initial public offering, net of offering costs and underwriter fees / asset purchase agreements	193,053									193,053
Issuance of common shares upon closing of initial public offering, net of offering costs and underwriter fees / asset purchase agreements, shares								12,500,000
Share-based compensation expense	426									426
Net loss	(44,733)												(44,733)
Ending Balance at Jun. 30, 2020	315,207									405,032			(89,825)
Ending Balance (in shares) at Jun. 30, 2020								41,664,044
Issuance of common shares upon exercise of common share warrants								38,340,000
Share-based compensation expense	1,241									1,241
Unrealized (loss) gain on investments	(1)														(1)
Net loss	(9,993)												(9,993)
Ending Balance at Sep. 30, 2020	306,454									406,273			(99,818)		(1)
Ending Balance (in shares) at Sep. 30, 2020								41,702,384,000
Beginning Balance at Dec. 31, 2020	294,513									407,672			(113,203)		44
Beginning Balance (in shares) at Dec. 31, 2020								41,725,797
Issuance of common shares upon exercise of stock options	130									130
Stock Issued During Period, Value, Stock Options Exercised								119,384
Share-based compensation expense	1,718									1,718
Unrealized (loss) gain on investments	239														239
Net loss	(17,529)												(17,529)
Ending Balance at Mar. 31, 2021	279,071									409,520			(130,732)		283
Ending Balance (in shares) at Mar. 31, 2021								41,845,181
Beginning Balance at Dec. 31, 2020	$ 294,513									407,672			(113,203)		44
Beginning Balance (in shares) at Dec. 31, 2020								41,725,797
Stock Issued During Period, Value, Stock Options Exercised	411,467
Unrealized (loss) gain on investments	$ 19
Net loss	(63,811)
Ending Balance at Sep. 30, 2021	246,495									423,446			(177,014)		63
Ending Balance (in shares) at Sep. 30, 2021								43,066,219,000
Beginning Balance at Mar. 31, 2021	279,071									409,520			(130,732)		283
Beginning Balance (in shares) at Mar. 31, 2021								41,845,181
Issuance of common shares upon exercise of stock options	210									210
Stock Issued During Period, Value, Stock Options Exercised								175,918,000
Issuance of common shares upon closing of initial public offering, net of offering costs and underwriter fees / asset purchase agreements		$ 8,924									$ 8,924
Issuance of common shares upon closing of initial public offering, net of offering costs and underwriter fees / asset purchase agreements, shares									600,000
Share-based compensation expense	2,145									2,145
Unrealized (loss) gain on investments	54														54
Net loss	(26,853)												(26,853)
Ending Balance at Jun. 30, 2021	263,551									420,799			(157,585)		337
Ending Balance (in shares) at Jun. 30, 2021								42,621,099
Issuance of common shares upon exercise of stock options	149									149
Stock Issued During Period, Value, Stock Options Exercised								116,165,000
Issuance of common shares upon closing of initial public offering, net of offering costs and underwriter fees / asset purchase agreements, shares									313,359,000
Issuance of common shares under ESPP	124									124
Issuance of common shares under ESPP (in shares)								15,596,000
Share-based compensation expense	2,374									2,374
Unrealized (loss) gain on investments	(274)														(274)
Net loss	(19,429)												(19,429)
Ending Balance at Sep. 30, 2021	$ 246,495									$ 423,446			$ (177,014)		$ 63
Ending Balance (in shares) at Sep. 30, 2021								43,066,219,000

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Non-Controlling Interest, Convertible Preferred Shares and Shareholders' Equity (Deficit) (Unaudited) (Parenthetical) $ in Thousands	3 Months Ended
	Jun. 30, 2020USD ($)
Issuance of common shares upon closing of initial public offering, offering costs and underwriter fees	$ 19,447
Class B Convertible Preferred Shares and Class B Preferred Share Tranche Right [Member]
Issuance of preferred shares and tranche right, issuance costs	6
Class B Preferred Exchangeable Shares and Class B Preferred Share Tranche Right [Member]
Issuance of preferred shares and tranche right, issuance costs	$ 2

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (63,811)	$ (64,948)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	6,237	2,025
Depreciation and amortization expense	450	373
Non-cash lease expense	793	3
Change in fair value of preferred share tranche right liability		32,722
Change in fair value of preferred share warrant liability		6,399
Amortization of premiums (accretion of discounts) on investments, net	1,361	24
Deferred tax benefit	(670)	(28)
Common shares issued to acquire in-process research & development	8,924
Foreign exchange loss	5
Changes in operating assets and liabilities:
Accounts receivable	(300)
Prepaid expenses and other current assets	(4,110)	(3,792)
Other non-current assets	(6,227)	(521)
Accounts payable	413	150
Accrued expenses	1,487	1,025
Deferred revenue	(546)
Income taxes payable	(2,800)	(117)
Operating lease liabilities	(619)
Net cash used in operating activities	(59,413)	(26,685)
Cash flows from investing activities:
Purchases of investments	(157,424)	(54,286)
Maturities of investments	165,255
Purchases of property and equipment	(953)	(1,063)
Net cash provided by (used in) investing activities	6,878	(55,349)
Cash flows from financing activities:
Proceeds from issuance of Class B convertible preferred shares and Class B preferred share tranche right, net of issuance costs		65,676
Proceeds from issuance of Class B preferred exchangeable shares of Fusion Pharmaceuticals (Ireland) Limited and Class B preferred share tranche right, net of issuance costs		6,722
Proceeds from the issuance of common shares upon closing of initial public offering, net of underwriter fees		197,625
Payment of offering costs	(216)	(4,572)
Proceeds from issuance of common shares upon exercise of stock options and ESPP	613
Net cash provided by financing activities	397	265,451
Net (decrease) increase in cash, cash equivalents and restricted cash	(52,138)	183,417
Cash, cash equivalents and restricted cash at beginning of period	92,408	67,121
Cash, cash equivalents and restricted cash at end of period	40,270	250,538
Supplemental disclosure of cash flow information:
Cash paid for income taxes	3,739	280
Right-of-use assets obtained in exchange for new operating lease liabilities	1,166
Increase in right-of-use assets and operating lease liabilities from operating lease modifications	911
Supplemental disclosure of non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable and accrued expenses	25
Issuance of warrants to purchase Class B preferred shares and Class B preferred exchangeable shares as a non-cash dividend to preferred shareholders		$ 1,382
Deferred offering costs included in accounts payable and accrued expenses	$ 60

Nature of the Business and Basi

Nature of the Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of the Business and Basis of Presentation	1. Nature of the Business and Basis of Presentation Fusion Pharmaceuticals Inc., together with its consolidated subsidiaries (“Fusion” or the “Company”), is a clinical-stage oncology company focused on developing next-generation radiopharmaceuticals as precision medicines. The Company was formed and subsequently incorporated as Fusion Pharmaceuticals Inc. in December 2014 The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, successful discovery and development of its product candidates, development by competitors of new technological innovations, dependence on key personnel, the ability to attract and retain qualified employees, protection of proprietary technology, compliance with governmental regulations, the impact of the COVID-19 pandemic, the ability to secure additional capital to fund operations and commercial success of its product candidates. Product candidates currently under development will require extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel, and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s drug development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. The accompanying condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and include the accounts of the Company and its wholly-owned subsidiary, Fusion Pharmaceuticals US Inc. The Company’s Irish subsidiary, Fusion Pharmaceuticals (Ireland) Unlimited Company, was majority-owned until June 2020 at which time it became a wholly-owned subsidiary and was subsequently re-registered in Ireland as an unlimited company in December 2020. As a result of consolidating the Irish subsidiary as majority-owned until June 2020, the Company reflected a non-controlling interest on the consolidated balance sheet; however, the Company did not recognize a non-controlling interest in the consolidated statements of operations and comprehensive loss as the majority-owned subsidiary had no operating activities and was an extension of the parent company. The Company's Irish subsidiary was liquidated and dissolved in September 2021. All intercompany accounts and transactions have been eliminated in consolidation. Reverse Share Split On June 19, 2020, the Company effected a one-for-5.339 reverse share split of its issued and outstanding common shares and a proportional adjustment to the existing conversion ratios for each class of the Company’s Preferred Shares (see Note 8) and Preferred Exchangeable Shares (see Note 8). Accordingly, all share and per share amounts for all periods presented in the accompanying condensed consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse share split and adjustment of the preferred share conversion ratios. Initial Public Offering On June 25, 2020, the Company completed an initial public offering (“IPO”) of its common shares and issued and sold 12,500,000 common shares at a public offering price of $17.00 per share, resulting in net proceeds of $193.1 million after deducting underwriting fees, and after deducting offering costs. Upon closing of the IPO, the Company’s outstanding preferred exchangeable shares automatically converted into convertible preferred shares then the outstanding convertible preferred shares automatically converted into shares of common shares (see Note 8). Upon conversion of the convertible preferred shares, the Company reclassified the carrying value of the convertible preferred shares to common shares and additional paid-in capital. In addition, the warrants to purchase the Company’s Series B convertible preferred shares and warrants to purchase preferred exchangeable shares of the Company’s Irish subsidiary were converted into warrants to purchase the Company’s common shares upon the closing of the IPO. As a result, the warrant liability was remeasured a final time on the closing date of the IPO and reclassified to shareholders’ equity (deficit). In connection with the IPO on June 25, 2020, the Company filed an amended and restated articles of the corporation under laws governed by the Canada Business Corporations Act Basis of Presentation The accompanying condensed consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. Since inception, the Company has funded its operations primarily with proceeds from sales of its convertible preferred shares, including borrowings under a convertible promissory note, which converted into convertible preferred shares, proceeds from sales of its Irish subsidiary’s preferred exchangeable shares, and most recently with the proceeds from the IPO completed in June 2020. 19.4 63.8 10.0 $ 64.9 September 30, 2021 177.0 Impact of the COVID-19 Pandemic The COVID-19 pandemic, which began in December 2019 and has spread worldwide, has caused many governments to implement measures to slow the spread of the outbreak through quarantines, travel restrictions, heightened border security and other measures. The impact of this pandemic has been, and will likely continue to be, extensive in many aspects of society, which has resulted, and will likely continue to result, in significant disruptions to the global economy as well as businesses and capital markets around the world. The future progression of the pandemic and its effects on the Company’s business and operations are uncertain. In response to public health directives and orders and to help minimize the risk of the virus to employees, the Company has taken precautionary measures, including implementing work-from-home policies for certain employees. The impact of the virus and variants thereof, including work-from-home policies, may negatively impact productivity, disrupt the Company’s business, and delay its preclinical research and clinical trial activities and its development program timelines, the magnitude of which will depend, in part, on the length and severity of the restrictions and other limitations on the Company’s ability to conduct its business in the ordinary course. Specifically, the Company has experienced material delays in patient recruitment and enrollment in its ongoing Phase 1 clinical trial of FPI-1434 as a result of continued resourcing issues related to COVID-19 at trial sites and potentially due to concerns among patients about participating in clinical trials during a public health emergency. The Company may not be able to enroll additional patient cohorts on its planned timeline due to disruptions at its clinical trial sites and is unable to predict how the COVID-19 pandemic may affect its ability to successfully progress its clinical programs in the future. Other impacts to the Company’s business may include temporary closures of its suppliers or other third parties upon whom the Company relies and disruptions or restrictions on its employees’ ability to travel. Any prolonged material disruption to the Company’s employees, suppliers or other third parties upon whom the Company relies could adversely impact the Company’s preclinical research and clinical trial activities, financial condition and results of operations, including its ability to obtain financing. The Company is monitoring the potential impact of the COVID-19 pandemic, including variants thereof, on its business and condensed consolidated financial statements. To date, the Company has not incurred impairment losses in the carrying values of its assets as a result of the pandemic and it is not aware of any specific related event or circumstance that would require it to revise its estimates reflected in these condensed consolidated financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses, the valuations of common shares, preferred share tranche rights and preferred share warrants prior to the closing of the IPO, valuations of share-based awards and revenue recognition. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ from those estimates or assumptions. Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of September 30, 2021, the condensed consolidated statement of operations and comprehensive loss, and the condensed consolidated statement of non-controlling interest, convertible preferred shares and shareholders’ equity (deficit) for the three and nine months ended September 30, 2021 and 2020, and the condensed consolidated statement of cash flows for the nine months ended September 30, 2021 and 2020 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2021 and the results of its operations for three and nine months ended September 30, 2021 and 2020 and its cash flows for the nine months ended September 30, 2021 and 2020. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2021 and 2020 are also unaudited. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of results to be expected for the year ending December 31, 2021, any other interim periods, or any future year or period. The accompanying balance sheet as of December 31, 2020 has been derived from the Company’s audited financial statements for the year ended December 31, 2020. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. These unaudited interim condensed consolidated financial statements should be read in conjunction with the audited annual consolidated financial statements as of December 31, 2020 included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 25, 2021. Foreign Currency and Currency Translation The reporting currency of the Company is the U.S. dollar. The functional currency of the Company’s operating company in Canada, operating company in the U.S. and non-operating company in Ireland is also the U.S. dollar. As a result, the Company records no cumulative translation adjustments related to translation of unrealized foreign exchange gains or losses. For the remeasurement of local currencies to the U.S. dollar functional currency of the Canadian and Irish entities, assets and liabilities are translated into U.S. dollars at the exchange rate in effect on the balance sheet date, and income items and expenses are translated into U.S. dollars at the average exchange rate in effect during the period. Resulting transaction gains (losses) are included in other income (expense), net in the consolidated statements of operations and comprehensive loss, as incurred. Adjustments that arise from exchange rate changes on transactions denominated in a currency other than the local currency are included in other income (expense), net in the consolidated statements of operations and comprehensive loss, as incurred. During the three and nine months ended September 30, 2021, the Company recorded less than ($0.1) million and $0.1 million, respectively, of foreign currency gains (losses) in the condensed consolidated statements of operations and comprehensive loss. During the three and nine months ended September 30, 2020, the Company recorded less than ($0.1) Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents consist of standard checking accounts, money market accounts, and all highly liquid investments with an original maturity of three months or less at the date of purchase. As of September 30, 2021 and December 31, 2020, the Company was required to maintain separate cash balances of $0.3 million to collateralize corporate credit cards with a bank, which was classified as restricted cash, current, on its condensed consolidated balance sheets. The Company also maintained a $0.1 million guaranteed investment certificate to fulfill certain contractual obligations which was classified as restricted cash, current, as of September 30, 2021 and December 31, 2020. In connection with the Company’s lease agreement entered into in October 2019 (see Note 13), the Company maintains a letter of credit of $1.5 million for the benefit of the landlord. As of September 30, 2021, $0.3 million and $1.2 million of the underlying cash balance collateralizing this letter of credit was classified as restricted cash, current and non-current, respectively, on the Company’s condensed consolidated balance sheets based on the release date of the restrictions of this cash. As of December 31, 2020, the entire underlying cash balance collateralizing this letter of credit was classified as restricted cash, non-current, on the Company’s condensed consolidated balance sheets. As of September 30, 2021 and December 31, 2020 , the cash , cash equivalents and restricted cash of $ 40.3 million and $ million, respectively, presented in the condensed consolidated statements of cash flows included cash and cash equivalents of $ 38.4 million and $ million, respectively, and restricted cash of $ million for both periods . Investments The Company determines the appropriate classification of its investments in debt securities at the time of purchase and re-evaluates such determination at each balance sheet date. The Company classifies its investments as current or non-current based on each instrument’s underlying maturity date. Investments with original maturities of greater than three months and less than twelve months are classified as current and are included in short-term investments in the condensed consolidated balance sheets. Investments with remaining maturities greater than one year from the balance sheet date are classified as non-current and are included in long-term investments in the condensed consolidated balance sheets. The Company’s investments are classified as available-for-sale, are reported at fair value and consist of U.S. government agency securities, corporate bonds, and commercial paper. Unrealized gains and losses are included in other comprehensive income (loss) as a component of shareholders’ equity (deficit) until realized. Amortization and accretion of premiums and discounts are recorded in interest income (expense). Realized gains and losses on debt securities are included in other income (expense), net. If any adjustment to fair value reflects a decline in value of the investment, the Company considers all available evidence to evaluate the extent to which the decline is other than temporary and, if so, marks the investment to market on the Company’s condensed consolidated statements of operations and comprehensive loss. Deferred Offering Costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of an equity financing, these costs are recorded as a reduction of the proceeds from the offering, either as a reduction to the carrying value of the preferred exchangeable shares or convertible preferred shares or in shareholders’ equity (deficit) as a reduction of additional paid-in capital generated as a result of the offering. Should an in-process equity financing be abandoned, the deferred offering costs would be expensed immediately as a charge to operating expenses in the consolidated statements of operations and comprehensive loss. The Company recorded $0.3 million of deferred offering costs as of September 30, 2021 in other non-current assets and did not record any deferred offering costs as of December 31, 2020. Collaborative Arrangements The Company considers the nature and contractual terms of arrangements and assesses whether an arrangement involves a joint operating activity pursuant to which the Company is an active participant and is exposed to significant risks and rewards dependent on the commercial success of the activity. If the Company is an active participant and is exposed to significant risks and rewards dependent on the commercial success of the activity, the Company accounts for such arrangement as a collaborative arrangement under ASC 808, Collaborative Arrangements For arrangements determined to be within the scope of ASC 808 where a collaborative partner is not a customer for certain research and development activities, the Company accounts for payments received for the reimbursement of research and development costs as a contra-expense in the period such expenses are incurred. This reflects the joint risk sharing nature of these activities within a collaborative arrangement. The Company classifies payments owed or receivables recorded as other current liabilities or prepaid expenses and other current assets, respectively, in the Company’s consolidated balance sheets. If payments from the collaborative partner to the Company represent consideration from a customer in exchange for distinct goods and services provided, then the Company accounts for those payments within the scope of ASC 606, Revenue from Contracts with Customers Revenue from Contracts with Customers In accordance with ASC 606, the Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, it performs the following five steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations within the contract and (v) recognize revenue when (or as) the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it determines that it is probable it will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within the contract to determine whether each promised good or service is a performance obligation. The promised goods or services in the Company’s arrangements typically consist of a license to the Company’s intellectual property and/or research and development services. The Company may provide customers with options to additional items in such arrangements, which are accounted for separately when the customer elects to exercise such options, unless the option provides a material right to the customer. Performance obligations are promises in a contract to transfer a distinct good or service to the customer that (i) the customer can benefit from on its own or together with other readily available resources, and (ii) is separately identifiable from other promises in the contract. Goods or services that are not individually distinct performance obligations are combined with other promised goods or services until such combined group of promises meet the requirements of a performance obligation. The Company determines transaction price based on the amount of consideration the Company expects to receive for transferring the promised goods or services in the contract. Consideration may be fixed, variable, or a combination of both. At contract inception for arrangements that include variable consideration, the Company estimates the probability and extent of consideration it expects to receive under the contract utilizing either the most likely amount method or expected amount method, whichever best estimates the amount expected to be received. The Company then considers any constraints on the variable consideration and includes in the transaction price variable consideration to the extent it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. The Company then allocates the transaction price to each performance obligation based on the relative standalone selling price and recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to the customer and the performance obligation is satisfied. For performance obligations which consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The Company records amounts as accounts receivable when the right to consideration is deemed unconditional. Amounts received, or that are unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract are recognized as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as the current portion of deferred revenue. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. The Company’s revenue generating arrangements typically include upfront license fees, milestone payments and/or royalties. If a license is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from nonrefundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. At the inception of an agreement that includes research and development milestone payments, the Company evaluates each milestone to determine when and how much of the milestone to include in the transaction price. The Company first estimates the amount of the milestone payment that the Company could receive using either the expected value or the most likely amount approach. The Company primarily uses the most likely amount approach as this approach is generally most predictive for milestone payments with a binary outcome. Then, the Company considers whether any portion of the estimated amount is subject to the variable consideration constraint (that is, whether it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty). The Company updates the estimate of variable consideration included in the transaction price at each reporting date which includes updating the assessment of the likely amount of consideration and the application of the constraint to reflect current facts and circumstances. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). For the three and nine months ended September 30, 2021, the Company recorded $0.3 million and $0.8 million, respectively, of revenue under collaboration agreements. Please refer to Note 3, “Collaboration Agreement” for additional details regarding revenue recognition under the AstraZeneca Agreement. Business Combinations In determining whether an acquisition should be accounted for as a business combination or asset acquisition, the Company first determines whether substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets. If this is the case, the single identifiable asset or the group of similar assets is not deemed to be a business, and is instead deemed to be an asset. If this is not the case, the Company then further evaluates whether the single identifiable asset or group of similar identifiable assets and activities includes, at a minimum, an input and a substantive process that together significantly contribute to the ability to create outputs. If so, the Company concludes that the single identifiable asset or group of similar identifiable assets and activities is a business. The Company accounts for business combinations using the acquisition method of accounting. Application of this method of accounting requires that (i) identifiable assets acquired (including identifiable intangible assets) and liabilities assumed generally be measured and recognized at fair value as of the acquisition date and (ii) the excess of the purchase price over the net fair value of identifiable assets acquired and liabilities assumed be recognized as goodwill, which is not amortized for accounting purposes but is subject to testing for impairment at least annually. Acquired in-process research and development (“IPR&D”) is recognized at fair value and initially characterized as an indefinite-lived intangible asset, irrespective of whether the acquired IPR&D has an alternative future use. Transaction costs related to business combinations are expensed as incurred. Determining the fair value of assets acquired and liabilities assumed in a business combination requires management to use significant judgment and estimates, especially with respect to intangible assets. During the measurement period, which extends no later than one year from the acquisition date, the Company may record certain adjustments to the carrying value of the assets acquired and liabilities assumed with the corresponding offset to goodwill. After the measurement period, all adjustments are recorded in the consolidated statements of operations as operating expenses or income. To date, the Company has not recorded any acquisitions as a business combination. Asset Acquisitions The Company measures and recognizes asset acquisitions that are not deemed to be business combinations based on the cost to acquire the assets, which includes transaction costs. Goodwill is not recognized in asset acquisitions. In an asset acquisition, the cost allocated to acquire IPR&D with no alternative future use is charged to expense at the acquisition date. Contingent consideration in asset acquisitions payable in the form of cash is recognized when payment becomes probable and reasonably estimable, unless the contingent consideration meets the definition of a derivative, in which case the amount becomes part of the asset acquisition cost when acquired. Contingent consideration payable in the form of a fixed number of the Company’s own shares is measured at fair value as of the acquisition date and recognized when the issuance of the shares becomes probable. Upon recognition of the contingent consideration payment, the amount is included in the cost of the acquired asset or group of assets, or, if related to IPR&D with no alternative future use, charged to expense. Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. Prior to the settlement of the Company’s preferred share tranche right liability and prior to the conversion of the Company’s preferred share warrant liability , these instruments were carried at fair value, determined according to Level 3 inputs in the fair value hierarchy described above (see Note 4 ). The Company’s cash equivalents and investments are carried at fair value, determined according to the fair value hierarchy described above (see Note 4 ). The carrying values of the Company’s amounts due for refundable investment tax credits and Canadian harmonized sales tax, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these liabilities. Preferred Share Tranche Right Liability The subscription agreements for the Company’s Class B convertible preferred shares (see Note 8) and its Irish subsidiary’s Class B preferred exchangeable shares (see Note 8) provided investors the right, or obligated investors, to participate in subsequent offerings of Class B convertible preferred shares or Class B preferred exchangeable shares together with Class B special voting shares in the event that specified development or regulatory milestones were achieved (the “Class B preferred share tranche right liability”). The Company classified these preferred share tranche rights as a liability on its consolidated balance sheets as each preferred share tranche right was a freestanding financial instrument that may have required the Company to transfer assets upon the achievement of specified milestone events. Each preferred share tranche right liability was initially recorded at fair value upon the date of issuance of each preferred share tranche right and was subsequently remeasured to fair value at each reporting date. Changes in the fair value of the preferred share tranche right liability were recognized as a component of other income (expense) in the consolidated statement of operations and comprehensive loss. Changes in the fair value of the preferred share tranche right liability were recognized until the respective preferred share tranche right was settled upon achievement of the specified milestones or it expired. On May 15, 2020, the Company achieved the specified regulatory milestone associated with the Class B preferred share tranche right (see Note 8), which triggered the requirement of the Class B shareholders to participate in the Milestone Financing. Upon closing of the Milestone Financing on June 2, 2020, the Company issued and sold 36,806,039 Class B preferred shares at a price of $1.5154 per share and 4,437,189 Class B special voting shares at a price of $0.000001 per share and the Company’s Irish subsidiary issued and sold 4,437,189 Class B preferred exchangeable shares at a price of $1.5154 per share, for aggregate gross proceeds of $62.5 million. The Class B preferred share tranche right liability (see Note 8) was settled in connection with the achievement of the regulatory milestone associated with the Class B preferred share tranche right. Specifically, the fair value of the Class B preferred share tranche right liability was remeasured for the last time as of the Milestone Financing closing date, resulting in the Company recognizing a loss in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2020 of $32.7 million for the change in the fair value of the tranche right liability between December 31, 2019 and June 2, 2020. Immediately thereafter, the balance of the Class B preferred share tranche right liability of $39.6 million was reclassified to Class B convertible preferred shares in an amount of $35.3 million and to non-controlling interest in the Company’s Irish subsidiary in an amount of $4.3 million on the consolidated balance sheet. For the nine months ended September 30, 2020, the Company recognized a loss of $32.7 million in the condensed consolidated statement of operations and comprehensive loss for the change in the fair value of the tranche right liability. Preferred Share Warrant Liability The Company classified warrants to purchase its convertible preferred shares and warrants to purchase preferred exchangeable shares of the Company’s Irish subsidiary as a liability on its consolidated balance sheets as these warrants were freestanding financial instruments that may have required the Company to transfer assets upon exercise (see Note 8). The preferred share warrant liability, which consisted of warrants to purchase Class B convertible preferred shares of the Company and warrants to purchase Class B preferred exchangeable shares of the Company’s Irish subsidiary, were initially recorded at fair value upon the date of issuance of each warrant and were subsequently remeasured to fair value at each reporting date. Changes in the fair value of the preferred share warrant liability were recognized as a component of other income (expense) in the consolidated statement of operations and comprehensive loss. Changes in the fair value of the preferred share warrant liability were recognized until each respective warrant was exercised, expired or qualified for equity classification. Upon the closing of the IPO, the warrants to purchase its convertible preferred shares and warrants to purchase preferred exchangeable shares of the Company’s Irish subsidiary were converted into warrants to purchase shares of the Company’s common shares. As a result, the warrant liability was remeasured a final time on the closing date of the IPO and reclassified to shareholders’ equity (deficit) as the warrants qualify for equity classification. Leases Prior to January 1, 2021, the Company accounted for leases in accordance with ASC 840, Leases inclusive of rent escalation, holidays and lease incentives, on a straight-line basis over the lease term. The difference between rent expense recorded and the amount paid was charged to deferred rent. The Company presented lease incentives as deferred rent and amortized the incentives as a reduction to rent expense on a straight-line basis over the lease term. The Company classified deferred rent as current and noncurrent liabilities based on the portion of the deferred rent that was scheduled to mature within the proceeding twelve months. Effective January 1, 2021, the Company accounts for leases in accordance with ASC 842, Leases A right-of-use asset represents the economic benefit conveyed to the Company by the right to use the underlying asset over the lease term. A lease liability represents the obligation to make lease payments arising from the lease. The Company records amortization of operating right-of-use assets and accretion of lease liabilities as a single lease cost on a straight-line basis over the lease term. The Company elected the practical expedient to not separate lease and non-lease components and therefore measures each lease payment as the total of the fixed lease and associated non-lease components. Lease liabilities are measured at the lease commencement date and calculated as the present value of the future lease payments in the contract using the rate implicit in the contract, when available. If an implicit rate is not readily determinable, the Company uses its incremental borrowing rate measured as the rate at which the Company could borrow, on a fully collateralized basis, a commensurate loan in the same currency over a period consistent with the lease term at the commencement date. Right-of-use assets are measured as the lease liability plus initial direct costs and prepaid lease payments, less lease incentives granted by the lessor. The lease term is measured as the noncancelable period in the contract, adjusted for any options to extend or terminate when it is reasonably certain the Company will extend the lease term via such options based on an assessment of economic factors present as of the lease commencement date. The Company elected the practical expedient to not recognize leases with a lease term of twelve months or less. The Company assesses its right-of-use assets for impairment consistent with the assessment performed for long-lived assets used in operations. If an impairment is recognized on operating lease right-of-use assets, the lease liability continues to be recognized using the same effective interest method as before the impairment and the operating lease right-of-use asset is amortized over the remaining term of the lease on a straight-line basis. The Company’s operating leases are presented in the condensed consolidated balance sheet as operating lease right-of-use assets, classified as noncurrent assets, and operating lease liabilities, classified as current and noncurrent liabilities based on the discounted lease payments to be made within the proceeding twelve months. Variable costs associated with a lease, such as maintenance and utilities, are not included in the measurement of the lease liabilities and right-of-use assets but rather are expensed when the events determining the amount of variable consideration to be paid have occurred. Research, Development and Manufacturing Contract Costs and Accruals The Company has entered into various research, development and manufacturing contracts with research institutions and other companies. These agreements are generally cancelable, and related costs are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research, development and manufacturing costs. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of outstanding obligations to those third parties as of period end. Any accrual estimates are based on a number of factors, including the Company’s knowledge of the progress towards co

Collaboration Agreement

Collaboration Agreement	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration Agreement	3 . Collaboration Agreement Strategic Collaboration Agreement with AstraZeneca UK Limited On October 30, 2020, the Company and AstraZeneca entered into the AstraZeneca Agreement pursuant to which the Company and AstraZeneca will work to jointly discover, develop and commercialize next-generation alpha-emitting radiopharmaceuticals and combination therapies for the treatment of cancer globally by leveraging the Company’s Targeted Alpha Therapies, or TATs, platform and expertise in radiopharmaceuticals with AstraZeneca’s leading portfolio of antibodies and cancer therapeutics, including DNA damage response inhibitors (“DDRis”). Each party retains full ownership over its existing assets. The AstraZeneca Agreement consists of two distinct collaboration programs: novel TATs and combination therapies. Under the AstraZeneca Agreement, the parties may develop up to three novel TATs (the “Novel TATs Collaboration”). The parties will also evaluate up to five potential combination strategies involving the Company’s existing assets, including the Company’s lead candidate FPI-1434, in combination with certain of AstraZeneca’s existing therapeutics for the treatment of various cancers (the “Combination Therapies Collaboration”). The AstraZeneca Agreement expires on a TAT-by-TAT and combination-by-combination basis upon the later of the expiration of development and exclusivity obligations relating to such TAT or combination or, if such TAT or combination is commercialized as a product under the AstraZeneca Agreement, the expiration of the commercial life of such product. The Company and AstraZeneca can each terminate the AstraZeneca Agreement for the other party’s uncured material breach following the applicable notice period. Each of the Company and AstraZeneca may also terminate the AstraZeneca Agreement with respect to any TAT or combination product if such party determines that the continued development of such TAT or combination product is not commercially viable, or for a material safety issue with respect to such TAT or combination product. Novel TATs Collaboration As part of the Novel TATs Collaboration, the parties may develop up to three novel TATs. The Company and AstraZeneca will share development costs equally (with each party responsible for the cost of its own supply in connection with such development). Either party has the right to opt out of the co-development and co-commercialization arrangement at pre-determined timepoints and obtain exclusive rights to a novel TAT in exchange for milestone payments to the other party of up to $145.0 million per novel TAT and a low or high single-digit royalties on future sales (depending on the opt out time point). If neither party opts out, and unless otherwise agreed by the parties, AstraZeneca will lead worldwide commercialization activities for the novel TATs, subject to the Company’s option to co-promote the TATs in the U.S. All profits and losses resulting from such commercialization activities will be shared equally. The Novel TATs Collaboration is within the scope of ASC 808 as the Company and AstraZeneca are both active participants in the research and development activities and are exposed to significant risks and rewards that are dependent on commercial success of the activities of the arrangement. The research and development activities are a unit of account under the scope of ASC 808 and are not promises to a customer under the scope of ASC 606. The Company records its portion of the research and development expenses as the related expenses are incurred. All payments received or amounts due from AstraZeneca for reimbursement of shared costs are accounted for as an offset to research and development expense. For the three and nine months ended September 30, 2021, the Company incurred $1.6 million and $2.0 million, respectively, in gross research and development expenses relating to the Novel TATs Collaboration which was offset by $0.8 million and $1.0 million, respectively, in amounts due from AstraZeneca for reimbursement of shared costs. As of September 30, 2021, the Company recorded $0.9 million due from AstraZeneca for reimbursement of shared costs in prepaid expenses and other current assets. Combination Therapies Collaboration As part of the Combination Therapies Collaboration, the parties will evaluate up to five potential combination strategies involving the Company’s existing assets, including the Company’s lead candidate FPI-1434, in combination with certain of AstraZeneca’s existing therapeutics for the treatment of various cancers. The Company received an upfront payment of $5.0 million from AstraZeneca in December 2020 associated with the Combination Therapies Collaboration. AstraZeneca will fully fund all research and development activities for the combination strategies, until such point as the Company may opt-in to the clinical development activities. The Company also has the right to opt-out of clinical development activities relating to these combination therapies. In such instance, the Company will be responsible for repaying its share of the development costs via a royalty on the additional combination sales only if its drug is approved on the basis of clinical development solely conducted by AstraZeneca, in which case the royalty payments shall also include a variable risk premium based on the number of the Company’s product candidates to have received regulatory approval at that time. Each party will have the sole right, on a country-by-country basis, to commercialize its respective contributed compound as a component of any combination therapy for which such party’s contributed compound may be commercialized under a separate marketing authorization from the other party’s contributed compound to such combination therapy. The parties will negotiate in good faith on a combination therapy-by-combination therapy basis the terms and conditions to co-commercialize any combination therapy that is to be commercialized under a single marketing authorization. During the period of time commencing with the inclusion of an available molecular target in the selection pool for development as a combination therapy and ending upon the end of the nomination period or earlier removal of such combination target from such pool, the Company will not undertake any preclinical or clinical studies combining the Company’s TAT platform with any compound modulating the activity of such combination target. Following selection of a target under the AstraZeneca Agreement and payment of an exclusivity fee by AstraZeneca, and provided that AstraZeneca enrolls its first patient in a clinical trial as further defined in the AstraZeneca Agreement within a pre-defined period of time of such selection, the Company will not undertake any preclinical or clinical studies combining the Company’s TAT platform with compounds modulating the same combination target for the duration of the evaluation period for such combination target, as further defined in the AstraZeneca Agreement. Within a certain time period following initiation of the evaluation period with respect to a combination target, AstraZeneca has the exclusive right to undertake, alone or in collaboration with the Company, all further clinical or preclinical combination studies with respect to a combination target by paying certain exclusivity fees. The Company is eligible to receive future payments of up to $ 40.0 million, including those for the achievement of certain clinical milestones and exclusivity fees. The Company determined the research and development activities associated with the Combination Therapies Collaboration are a key component of its central operations and AstraZeneca has contracted with the Company to obtain goods and services which are an output of the Company’s ordinary activities in exchange for consideration. Further, the Company does not share the risks and rewards of the underlying research activities making AstraZeneca a customer for the Combination Therapies Collaboration which falls within the scope of ASC 606. To determine the appropriate amount of revenue to be recognized under ASC 606, the Company performed the following steps: (i) identify the promised goods or services in the contract, (ii) determine whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract, (iii) measure the transaction price, including the constraint on variable consideration, (iv) allocate the transaction price to the performance obligations and (v) recognize revenue when (or as) the Company satisfies each performance obligation. Under ASC 606 the Company accounts for (i) the license it conveyed to AstraZeneca with respect to certain intellectual property and (ii) the obligations to perform research and development services as part of the Combination Therapies Collaboration as a single performance obligation under the AstraZeneca Agreement. The Company concluded AstraZeneca’s right to purchase exclusive options to obtain certain development, manufacturing and commercialization rights represent customer options that are not performance obligations as they do not contain any discounts or other rights that would be considered a material right in the arrangement. Such options will be accounted for upon AstraZeneca’s election. The Company determined the transaction price under ASC 606 at the inception of the AstraZeneca Agreement to be the $5.0 million upfront payment. The cost reimbursement payments for all costs incurred by the Company under the Combination Therapies Collaboration represent variable consideration that is not constrained. Additionally, the clinical milestone payments represent variable consideration that is constrained. In making this assessment, the Company considered several factors, including the fact that achievement of the milestones are outside its control and contingent upon the future success of clinical trials and AstraZeneca’s actions. The payments related to the achievement of certain clinical milestones do not relate to separate, distinct performance obligations. Under ASC 606, the Company recognizes revenue using the cost-to-cost method, which it believes best depicts the transfer of control to the customer. Under the cost-to-cost method, the extent of progress towards completion is measured based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the identified performance obligation. Under this method, revenue is recorded as a percentage of the estimated transaction price based on the extent of progress towards completion. Under ASC 606, the estimated transaction price includes variable consideration that is not constrained. The Company does not include variable consideration to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will occur when any uncertainty associated with the variable consideration is resolved. The estimate of the Company’s measurement of progress and estimate of variable consideration to be included in the transaction price will be updated at each reporting date as a change in estimate. For the clinical milestone payments, the Company utilizes the most likely amount method to determine the amounts recognized and timing of recognition. Once the constraint is removed, the clinical milestone payments will be accounted for with the research and development services for the purposes of revenue recognition which will occur over time as the services are provided. Upon the achievement of any milestone for specified clinical development events, the Company will utilize the same cost-to-cost model with a cumulative catch-up recognized in the period in which any such event occurs. The Company will re-evaluate the transaction price at the end of each reporting period and as uncertain events are resolved, or other changes in circumstances occur, adjust its estimate of the transaction price if necessary. As of December 31, 2020, the Company recorded the upfront fee as a contract liability for deferred revenue in its condensed consolidated balance sheet as it had yet to provide any services under the AstraZeneca Agreement. The following table presents changes in the Company’s contract assets and liabilities for the nine months ended September 30, 2021 (in thousands): Balance as of Balance as of December 31, 2020 Additions Deductions September 30, 2021 Contract assets: Accounts receivable $ — $ 300 $ — $ 300 Contract liabilities: Deferred revenue $ 5,000 $ — $ (546 ) $ 4,454 During the three and nine months ended September 30, 2021 and 2020, the Company recognized the following revenue (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Revenue recognized in the period from: Amounts included in deferred revenue at the beginning of the period $ 146 $ — $ 546 $ — The current portion of deferred revenue and deferred revenue, net of current portion, are $2.3 million and $2.2 million as of September 30, 2021, respectively, which reflects the Company’s estimate of the revenue it expects to recognize within the next 12 months and beyond 12 months, respectively. The Company expects to recognize the revenue associated with the AstraZeneca Agreement in subsequent periods through the year ending December 31, 2024.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	4 . Fair Value Measurements The following tables present information about the Company’s financial assets and liabilities that are measured at fair value on a recurring basis and indicates the level of the fair value hierarchy used to determine such fair values (in thousands): Fair Value Measurements as of September 30, 2021 Using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 12,040 $ — $ — $ 12,040 U.S. Government agencies — 10,949 — 10,949 Investments: Commercial paper — 24,788 — 24,788 Corporate bonds — 28,365 — 28,365 Municipal bonds — 17,021 — 17,021 Canadian Government agencies — 5,682 — 5,682 U.S. Government agencies — 123,936 — 123,936 $ 12,040 $ 210,741 $ — $ 222,781 Fair Value Measurements as of December 31, 2020 Using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 19,277 $ — $ — $ 19,277 Commercial paper — 1,000 — 1,000 Corporate bonds — 950 — 950 Canadian Government agencies — 2,347 — 2,347 Investments: Commercial paper — 34,471 — 34,471 Corporate bonds — 26,857 — 26,857 Municipal bonds — 1,090 — 1,090 Canadian Government agencies — 9,457 — 9,457 U.S. Government agencies — 137,089 — 137,089 $ 19,277 $ 213,261 $ — $ 232,538 During the nine months ended September 30, 2021 and the year ended December 31, 2020, there were no transfers between Level 1, Level 2 and Level 3.

Investments

Investments	9 Months Ended
	Sep. 30, 2021
Investments Debt And Equity Securities [Abstract]
Investments	5 . Investments Investments consisted of the following (in thousands): September 30, 2021 Amortized Cost Fair Value Due within one year or less $ 154,155 $ 154,238 Due after one year through three years 45,574 45,554 $ 199,729 $ 199,792 December 31, 2020 Amortized Cost Fair Value Due within one year or less $ 131,857 $ 131,882 Due after one year through three years 77,063 77,082 $ 208,920 $ 208,964 As of September 30, 2021, the amortized cost and estimated fair value of investments, by contractual maturity, was as follows (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Current Non-Current Commercial paper $ 24,787 $ 1 $ — $ 24,788 $ 24,788 $ — Corporate bonds 28,327 43 (5 ) 28,365 23,856 4,509 Municipal bonds 17,023 2 (4 ) 17,021 14,766 2,255 Canadian Government agencies 5,637 45 — 5,682 4,578 1,104 U.S. Government agencies 123,955 10 (29 ) 123,936 86,250 37,686 $ 199,729 $ 101 $ (38 ) $ 199,792 $ 154,238 $ 45,554 As of December 31, 2020, the amortized cost and estimated fair value of investments, by contractual maturity, was as follows (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Current Non-Current Commercial paper $ 34,474 $ 1 $ (4 ) $ 34,471 $ 34,471 $ — Corporate bonds 26,855 22 (20 ) 26,857 9,446 17,411 Municipal bonds 1,090 — — 1,090 1,090 — Canadian Government agencies 9,405 52 — 9,457 6,154 3,303 U.S. Government agencies 137,096 8 (15 ) 137,089 80,721 56,368 $ 208,920 $ 83 $ (39 ) $ 208,964 $ 131,882 $ 77,082

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	9 Months Ended
	Sep. 30, 2021
Prepaid Expense And Other Assets Current [Abstract]
Prepaid Expenses and Other Current Assets	6 . Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following (in thousands): September 30, 2021 December 31, 2020 Prepaid external research and development expenses $ 3,446 $ 1,606 Prepaid insurance 3,247 2,067 Prepaid software subscriptions 434 146 Income tax receivable 232 — Interest receivable 461 504 Other receivable due from AstraZeneca 932 — Canadian harmonized sales tax receivable 360 290 Other 311 727 $ 9,423 $ 5,340

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Accrued Expenses	7 . Accrued Expenses Accrued expenses consisted of the following (in thousands): September 30, 2021 December 31, 2020 Accrued employee compensation and benefits $ 2,787 $ 2,551 Accrued external research and development expenses 2,239 1,037 Accrued professional and consulting fees 1,108 1,023 Other 12 48 $ 6,146 $ 4,659

Equity

Equity	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Equity	8 . Equity Common Shares On June 19, 2020, the Company effected a one-for-5.339 reverse share split of its issued and outstanding common shares and a proportional adjustment to the existing conversion ratios for each class of the Company’s Preferred Shares and Preferred Exchangeable Shares. Accordingly, all share and per share amounts for all periods presented in the accompanying condensed consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse share split and adjustment of the preferred share conversion ratios. On June 30, 2020, the Company closed its IPO of common shares and issued and sold 12,500,000 shares of common shares at a public offering price of $17.00 per share, resulting in net proceeds of approximately $193.1 million after deducting underwriting fees and offering costs. Upon the closing of the IPO, all outstanding voting and non-voting common shares were converted to a single class of common shares authorized by the Company’s articles of the corporation, as amended and restated. On July 2, 2021, the Company entered into an Open Market Sales Agreement SM the Sales Agreement, through an “at-the-market” equity offering program under which Jefferies LLC will act as the Company’s agent and/or principal (the “ATM Facility”). The ATM Facility provides that Jefferies LLC will be entitled to compensation for its services in an amount of up to 3.0 % of the gross proceeds of any shares sold under the ATM Facility. The Company has no obligation to sell any shares under the ATM Facility and may, at any time, suspend solicitation and offers under the Sales Agreement. As of September 30, 2021 , the Company has no t sold any shares under the Sales Agreement. As of September 30, 2021, the Company’s articles of the corporation, as amended and restated, authorized the Company to issue unlimited common shares, each with no Each common share entitles the holder to one vote on all matters submitted to a vote of the Company’s shareholders. Common shareholders are entitled to receive dividends, if any, as may be declared by the board of directors. Through September 30, 2021, no cash dividends had been declared or paid by the Company. Convertible Preferred Shares Prior to the IPO, the Company issued Class A convertible preferred shares (the “Class A preferred shares”) and Class B convertible preferred shares (the “Class B preferred shares” and, together with the Class A preferred shares, the “Preferred Shares”). As of December 31, 2020, the Company’s articles of the corporation, as amended and restated, authorized the Company to issue an aggregate of 132,207,290 Preferred Shares, respectively, each with no In March 2019, the Company completed its first closing of its Class B preferred shares and issued and sold 30,207,129 Class B preferred shares at a price of $1.5154 per share for gross proceeds of $45.8 million (the “2019 Preferred Share Financing”). In January 2020, the Company executed the First Amendment to the Class B Subscription Agreement (“Amended Class B Subscription Agreement”) whereby the Canada Pension Plan Investment Board (“CPP”) agreed to purchase an aggregate of $20.0 million of Class B preferred shares, at a price of $1.5154 per share, in two tranches. In January 2020, the Company issued and sold to CPP 6,598,917 Class B preferred shares, resulting in gross proceeds of $10.0 million (the “Additional Class B Closing”). The Company incurred issuance costs of $0.1 million in connection with this transaction. The rights and preferences of the Class B preferred shares sold under the Additional Class B Closing were the same as the rights and preferences of the Class B preferred shares issued and sold by the Company in March 2019. Accordingly, under the terms of the Amended Class B Subscription Agreement, upon the earlier occurrence of a specified development or specified regulatory milestone, CPP was obligated to purchase an additional 6,598,917 Class B preferred shares at a price of $1.5154 per share. The Company concluded that these rights or obligations of CPP to participate in the Milestone Financing of Class B preferred shares met the definition of a freestanding financial instrument that was required to be recorded as a liability at fair value as (i) the instruments are legally detachable and separately exercisable from the Class B preferred shares and (ii) the rights will require the Company to transfer assets upon future closings of the Class B preferred shares. Upon the Additional Class B Closing in January 2020, the Company recorded an additional liability for the preferred share tranche right of $1.1 million and a corresponding reduction to the carrying value of the Class B preferred shares. In May 2020, the Company achieved the specified regulatory milestone associated with the Class B preferred share tranche right, which triggered the requirement of the Class B shareholders to participate in the Milestone Financing. Upon closing of the Milestone Financing on June 2, 2020, the Company issued and sold 36,806,039 Class B preferred shares at a price of $1.5154 per share for aggregate proceeds of $55.8 million. The Class B preferred share tranche right liability was settled in connection with the achievement of the regulatory milestone associated with the Class B preferred share tranche right. Specifically, the fair value of the Class B preferred share tranche right liability was remeasured for the last time as of the Milestone Financing closing date, resulting in the Company recognizing a loss in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2020 of $32.7 million for the change in the fair value of the tranche right liability between December 31, 2019 and June 2, 2020. Immediately thereafter, the balance of the Class B preferred share tranche right liability of $39.6 million was reclassified to Class B convertible preferred shares in an amount of $35.3 million and to non-controlling interest in Fusion Pharmaceuticals (Ireland) Limited in an amount of $4.3 million on the consolidated balance sheet. For the nine months ended September 30, 2020, the Company recognized a loss of $32.7 million in the condensed consolidated statement of operations and comprehensive loss for the change in the fair value of the tranche right liability. Upon the closing of the IPO, the Company converted the then outstanding Class A and Class B preferred shares into common shares at a conversion ratio of 5.339 Preferred Share to one common share. Preferred Exchangeable Shares and Special Voting Shares In connection with each issuance and sale of its Class A preferred shares and Class B preferred shares, the Company’s Irish subsidiary issued and sold Class A and Class B preferred exchangeable shares (together, the “Preferred Exchangeable Shares”) to investors. Simultaneously with the issuance and sale of the Preferred Exchangeable Shares, the Company issued and sold its Class A and Class B special voting shares (together, the “Special Voting Shares”) to the same investors. Prior to the IPO, the Company’s Irish subsidiary’s amended constitution authorized it to issue an aggregate of 28,874,378 Preferred Exchangeable Shares and 29,747,987 Preferred Exchangeable Shares, respectively, with a par value of $0.001 per share. Prior to the IPO, the Company’s articles of the corporation, as amended and restated, authorized the Company to issue an aggregate of 28,874,378 Special Voting Shares and 29,747,987 Special Voting Shares, respectively, with a cash redemption value of $0.000001 per share. In March 2019, in connection with the first closing of Class B preferred shares, as described above, the Company’s Irish subsidiary issued and sold 4,437,189 Class B preferred exchangeable shares at a price of $1.5154 per share and the Company issued and sold 4,437,189 Class B special voting shares at a price of $0.000001 per share for aggregate gross proceeds of $6.7 million (the “2019 Preferred Exchangeable Share Financing”). In May 2020, the Company achieved the specified regulatory milestone associated with the Class B preferred share tranche right, which triggered the requirement of the Class B shareholders to participate in the Milestone Financing. Upon closing of the Milestone Financing on June 2, 2020, the Company issued and sold 4,437,189 Class B special voting shares at a price of $0.000001 per share and the Company’s Irish subsidiary issued and sold 4,437,189 Class B preferred exchangeable shares at a price of $1.5154 per share, for aggregate gross proceeds of $6.7 million. Upon the closing of the IPO, the Company converted all of the outstanding Class A and Class B preferred exchangeable shares and Special Voting Shares into Class A and Class B preferred shares on a one-for-one basis then converted the Class A and Class B preferred shares into common shares at a conversion ratio of 5.339 Preferred Share to one common share. Warrants In January 2020, in conjunction with the Company’s execution of the Amended Class B Subscription Agreement, the Company issued to the existing holders of Class B convertible preferred shares (excluding the investor in the Additional Class B Closing in January 2020) warrants to purchase 3,126,391 Class B convertible preferred shares, at an exercise price of $1.5154 per share, and Fusion Pharmaceuticals (Ireland) Limited issued to the existing holders of Class B preferred exchangeable shares warrants to purchase 873,609 Class B preferred exchangeable shares, at an exercise price of $1.5154 per share (collectively the “Preferred Share Warrants”). If the warrants to purchase Class B preferred exchangeable shares are exercised, at that same time, the shareholder is obligated to purchase from the Company an equal number of Class B special voting shares at a price of $0.000001 per share. The Preferred Share Warrants were issued for no consideration, and the specified exercise prices of each warrant are subject to adjustment for share dividends, share splits, combination or other similar recapitalization transactions as provided under the terms of the warrants. The Preferred Share Warrants were immediately exercisable and expire two years from the date of issuance or upon the earlier occurrence of specified qualifying events, which include the consummation of a Deemed Liquidation Event and the closing of a qualifying share sale (as defined in the articles of the corporation, as amended and restated). Upon the closing of a qualified public offering, on specified terms, all outstanding warrants to purchase Class B convertible preferred shares of the Company and warrants to purchase Class B preferred exchangeable shares of Fusion Pharmaceutics (Ireland) Limited will become warrants to purchase common shares of the Company. Upon issuance of the Preferred Share Warrants in January 2020, the Company recorded on its consolidated balance sheet a preferred share warrant liability of $1.4 million, equal to the issuance-date fair value of the Preferred Share Warrants, as well as a corresponding decrease of $1.3 million to additional paid-in capital, reducing that to zero, and an increase of $0.1 million to accumulated deficit for the remainder. The issuance of the Preferred Share Warrants was treated as a deemed dividend to existing preferred shareholders for purposes of the Company’s calculation of net loss per share attributable to common shareholders, and, as such, the aggregate value of the dividend to existing preferred shareholders was deducted from the Company’s net loss when computing net loss per share attributable to common shareholders (see Note 12). The Company remeasures the fair value of the liability associated with the Preferred Share Warrants at each reporting date and records any adjustments as a component of other income (expense) in the consolidated statements of operations and comprehensive loss. Upon the closing of the IPO, the warrants to purchase 3,126,391 of its convertible preferred shares and warrants to purchase 873,609 preferred exchangeable shares of the Company’s Irish subsidiary were converted into warrants to purchase 749,197 shares of the Company’s common shares at an exercise price of $8.10 per share. As a result, the warrant liability was remeasured a final time on the closing date of the IPO and reclassified to shareholders’ equity (deficit) as the warrants qualify for equity classification. For the nine months ended September 30, 2020 , the Company recognized a loss of $ 6.4 million as a component of other income (expense) in the condensed consolidated statement of operations and comprehensive loss to reflect an increase in fair value of the Preferred Share Warrant. On August 17, 2020, a holder of common share warrants exercised 97,381 common share warrants through a cashless exercise and the Company issued 38,340 common shares with the remaining 59,041 warrants being cancelled to settle the exercise price. As of September 30, 2021, 651,816 common share warrants remained outstanding.

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	9 . Share-based Compensation 2020 Stock Option and Incentive Plan On June 18, 2020, the Company’s board of directors adopted the 2020 Stock Option and Incentive Plan (the “2020 Plan”), which became effective on June 24, 2020. The 2020 Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock units, restricted stock awards, unrestricted stock awards, cash-based awards and dividend equivalent rights to the Company’s officers, employees, non-employee directors and consultants. The number of shares initially reserved for issuance under the 2020 Plan was 4,273,350, which was cumulatively increased on January 1, 2021 and shall be cumulatively increased each January 1 thereafter by 4% of the number of the Company’s common shares outstanding on the immediately preceding December 31 or such lesser number of shares determined by the Company’s compensation committee of the board of directors. The common shares underlying any awards that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of shares, expire or are otherwise terminated (other than by exercise) under the 2020 Plan and the 2017 Plan will be added back to the common shares available for issuance under the 2020 Plan. The total number of common shares reserved for issuance under the 2020 Plan was 6,151,833 shares as of September 30, 2021. As of September 30, 2021, 2,575,208 shares, remained available for future grant under the 2020 Plan. Shares that are expired, forfeited, canceled or otherwise terminated without having been fully exercised will be available for future grant under the 2020 Plan. 2017 Equity Incentive Plan The Company’s 2017 Equity Incentive Plan (the “2017 Plan”) provides for the Company to grant incentive stock options or nonqualified stock options, restricted share awards and restricted share units to employees, officers, directors and non-employee consultants of the Company. As of September 30, 2021 and December 31, 2020, no shares remained available for future grant under the 2017 Plan. Shares that are expired, forfeited, canceled or otherwise terminated without having been fully exercised will be available for future grant under the 2020 Plan. 2020 Employee Share Purchase Plan On June 18, 2020, the Company’s board of directors adopted the 2020 Employee Share Purchase Plan (the “ESPP”), which became effective on June 24, 2020. A total of 450,169 common shares were reserved for issuance under this plan. In addition, the number of common shares that may be issued under the ESPP was automatically increased on January 1, 2021 and shall be automatically increased each January 1 thereafter by the lesser of (i) 900,338 common shares, (ii) 1% of the number of the Company’s common shares outstanding on the immediately preceding December 31 and (iii) such lesser number of shares as determined by the Company’s compensation committee of the board of directors. As of September 30, 2021, 15,596 shares were issued under the ESPP. The total number of common shares reserved for issuance under the ESPP was 867,427 shares as of September 30, 2021. Stock Option Valuation The fair value of stock option grants is estimated using the Black-Scholes option-pricing model. The Company historically has been a private company and lacks company-specific historical and implied volatility information. Therefore, it estimates its expected share volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded share price. For options with service-based vesting conditions, the expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The expected term of stock options granted to non-employee consultants is equal to the contractual term of the option award. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The following table presents, on a weighted-average basis, the assumptions used in the Black-Scholes option-pricing model to determine the grant-date fair value of stock options granted: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Risk-free interest rate 1.02 % 0.33 % 0.85 % 0.70 % Expected term (in years) 6.1 6.0 6.1 6.0 Expected volatility 66.9 % 67.0 % 66.9 % 65.5 % Expected dividend yield 0 % 0 % 0 % 0 % Stock Options The following table summarizes the Company’s stock option activity since December 31, 2020: Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value (in years) (in thousands) Outstanding as of December 31, 2020 5,607,244 $ 6.45 8.2 $ 36,628 Granted 2,750,600 10.29 Exercised (411,467 ) 1.19 Forfeited/cancelled (297,089 ) 11.36 Outstanding as of September 30, 2021 7,649,288 $ 7.92 8.3 $ 18,916 Vested and expected to vest as of September 30, 2021 7,512,688 $ 7.85 8.3 $ 18,916 Options exercisable as of September 30, 2021 2,814,127 $ 4.37 7.1 $ 13,773 The aggregate intrinsic value of options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common shares for those options that had exercise prices lower than the fair value of the Company’s common shares. The intrinsic value for stock options exercised during the nine months ended September 30, 2021 was $3.3 million. The weighted-average grant-date fair value of stock options granted during the nine months ended September 30, 2021 and 2020 was $6.17 and $11.54 per share, respectively. Share-based Compensation Share-based compensation expense was classified in the condensed consolidated statements of operations and comprehensive loss as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development expenses $ 728 $ 288 $ 1,913 $ 506 General and administrative expenses 1,646 953 4,324 1,519 $ 2,374 $ 1,241 $ 6,237 $ 2,025 As of September 30, 2021, total unrecognized share-based compensation expense related to unvested share-based awards was $25.4 million, which is expected to be recognized over a weighted-average period of 2.8 years. Additionally, as of September 30, 2021, the Company has unrecognized share-based compensation expense related to unvested stock options with performance-based vesting conditions for which performance has not been deemed probable of $1.0 million.

License Agreements and Asset Ac

License Agreements and Asset Acquisitions	9 Months Ended
	Sep. 30, 2021
License Agreement [Abstract]
License Agreements and Asset Acquisitions	10 . License Agreements and Asset Acquisitions License Agreement with the Centre for Probe Development and Commercialization Inc. In November 2015, the Company entered into a license agreement with the Centre for Probe Development and Commercialization Inc. (“CPDC”), a related party (see Note 15) (the “CPDC Agreement”). Under the agreement, the Company was granted an exclusive, sublicensable, nontransferable, worldwide license under CPDC’s patent rights related to CPDC’s radiopharmaceutical linker technology to develop, market, make, use and sell certain products for all disease indications and uses in humans, whether diagnostic or therapeutic. The Company has the right to grant sublicenses of its rights. The CPDC Agreement was amended in 2017; however, there were no material changes to the terms of the CPDC Agreement. Also in 2017, the Company entered into a second license agreement with CPDC, under which the Company was granted an exclusive, sublicensable, worldwide license under CPDC’s patent rights related to certain CPDC radiopharmaceutical linker technology to develop, market, make, use and sell certain products for all disease indications and uses in humans. The Company has the right to grant sublicenses of its rights. The Company has no obligations under any of the agreements with CPDC to make any milestone payments or to pay any royalties or annual maintenance fees to CPDC. During the three and nine months ended September 30, 2021 and 2020, the Company did not make any payments to CPDC or recognize any research and development expenses under the license agreements with CPDC. License Agreement with ImmunoGen, Inc. In December 2016, the Company entered into a license agreement with ImmunoGen, Inc. (“ImmunoGen”) (the “ImmunoGen Agreement”). Under the agreement, the Company was granted an exclusive, sublicensable, worldwide license under ImmunoGen’s patent rights to use, develop, manufacture and commercialize any radiopharmaceutical conjugate that includes a certain compound and any resulting commercialized products. The Company has the right to grant sublicenses of its rights. Under the ImmunoGen Agreement, the Company paid an upfront fee of $0.2 million to ImmunoGen. In addition, the Company is obligated to make aggregate milestone payments to ImmunoGen of up to $15.0 million upon the achievement of specified development and regulatory milestones and of up to $35.0 million upon the achievement of specified sales milestones. The Company is also obligated to pay tiered royalties of a low to mid single-digit percentage based on annual net sales by the Company and any of its affiliates and sublicensees. Royalties will be paid by the Company on a country-by-country basis beginning upon the first commercial sale in such country until ten years following the date of the first commercial sale in the United States and five years following the date of the first commercial sale in all non-U.S. countries. In addition, the Company is responsible for all costs and expenses incurred related to the development, manufacture, regulatory approval and commercialization of all licensed products. Prior to regulatory approval of a licensed product in any country, the Company has the right to terminate the agreement upon 90 days’ prior written notice to ImmunoGen. Upon receipt of its first regulatory approval of a licensed product in any country, the Company has the right to terminate the agreement upon 180 days’ prior written notice to ImmunoGen. If the Company or ImmunoGen fails to comply with any of its obligations or otherwise breaches the agreement, the other party may terminate the agreement. The ImmunoGen Agreement expires upon the expiration date of the last-to-expire royalty term. During the three and nine months ended September 30, 2021 and 2020, the Company did not make any payments to ImmunoGen or recognize any research and development expenses under the ImmunoGen Agreement. Asset Acquisition from and License Agreement with MediaPharma S.r.l. In May 2019, the Company and MediaPharma S.r.l. (“MediaPharma”) entered into an asset acquisition and license agreement. Under the agreement, the Company purchased all right, title and interest to MediaPharma’s, and any of its affiliates’ and sublicensees’, patents to perform research and to develop, manufacture and commercialize a specified antibody that binds to targets for the prevention, treatment and diagnosis of all diseases and conditions. The Company accounted for this purchase as an asset acquisition. At the same time, the Company granted MediaPharma an exclusive, fully paid, worldwide, sublicensable license to use the specified compound for research, development, manufacturing and commercialization of a bispecific antibody drug conjugate, but not for use as a radiopharmaceutical. In connection with the asset acquisition, the Company paid an upfront fee of $0.2 million to MediaPharma. In addition, the Company is obligated to make aggregate milestone payments to MediaPharma of up to $1.5 million upon the achievement of specified development milestones and of up to $23.0 million upon the achievement of specified sales milestones. The Company is also obligated to pay royalties of a low single-digit percentage based on annual net sales by the Company. Royalties will be paid by the Company on a country-by-country basis beginning upon the first commercial sale in such country and will expire, on a country-by-country basis, upon the earlier of (i) eight years from the first commercial sale of a licensed product in such country, (ii) the date upon which all issued patents under the agreement have expired or (iii) the date upon which a product highly similar in composition to the licensed product and having no clinically meaningful differences is sold or marketed for sale in such country by a third party . The Company is not entitled to any payments from MediaPharma for use of the license to the specified compound granted to MediaPharma. During the three and nine months ended September 30, 2021 and 2020, the Company did not make any payments to MediaPharma or recognize any research and development expenses under the MediaPharma Agreement. Asset Acquisition from Rainier Therapeutics, Inc. and License Agreement with Genentech, Inc. On March 10, 2020 (the “Closing”), the Company and Rainier Therapeutics, Inc. (“Rainier”) entered into an asset acquisition agreement (the “Rainier Agreement”). Under the agreement, the Company purchased all rights, title and interest to Rainier’s, and any of its affiliates’ and sublicensees’, patents and other tangible and intangible assets to perform research and to develop, manufacture and commercialize a specified compound of antibody molecules that bind to targets for the prevention, treatment and diagnosis of all diseases and conditions only using such compound as an antibody drug conjugate. The Company concluded to account for this purchase as an asset acquisition as substantially all of the fair value of the gross assets acquired was concentrated in a single identifiable asset, the license rights. In connection with the asset acquisition, the Company paid an upfront fee of $1.0 million to Rainier and recognized this amount as research and development expense in the condensed consolidated statement of operations and comprehensive loss during the three months ended March 31, 2020, as the IPR&D acquired had no alternative future use as of the acquisition date. Unless the Rainier Agreement was terminated pursuant to its terms, which termination initially could not have occurred later than eight months following the Closing (the “Outside Date”), the Company was obligated to pay Rainier an additional amount of $3.5 million and to issue 313,359 of the Company’s common shares on the Outside Date. If the Rainier Agreement was not terminated by the Outside Date, the Company is also obligated to make aggregate milestone payments to Rainier of up to $22.5 million and to issue up to 156,679 of the Company’s common shares upon the achievement of specified development and regulatory milestones, of which a $2.0 million milestone payment and the issuance of 156,679 common shares are due upon the first patient dosed in a Phase 1 study of FPI-1966, and of up to $42.0 million upon the achievement of specified sales milestones. In the event the Company enters into a transaction with a non-affiliated party relating to the license or sale of substantially all the Company’s rights to develop the specified compound of antibody molecules, the Company will be obligated to pay Rainier a specified percentage of the revenue from such transaction, in an amount ranging from 10% to 30%, based on how long after the Closing the transaction takes place. The Rainier Agreement could have been terminated at any time prior to the Outside Date upon 30 days’ notice by the Company to Rainier or upon the mutual written consent of both parties. On October 8, 2020, the Company and Rainier entered into a first amendment to the Rainier Agreement (the “First Amended Rainier Agreement”) to extend certain terms of the Rainier Agreement. Specifically, the Outside Date was amended such that termination may not occur later than eleven months following the Closing, or February 10, 2021 (the “Revised Outside Date”). On February 8, 2021, the Company and Rainier entered into a second amendment to the First Amended Rainier Agreement, as amended (the “Second Amended Rainier Agreement”). Pursuant to the Second Amended Rainier Agreement, the Outside Date was further amended such that termination may not occur later than July 1, 2021, and such amendment was made in consideration for early payment of the additional $3.5 million owed to Rainier which the Company paid and recorded as research and development expense during the three months ended March 31, 2021. On May 26, 2021, the Company notified Rainier of its intent to continue development of the asset and issued 313,359 of its common shares to Rainier on July 1, 2021. During the three months ended September 30, 2021, the Company did not recognize any research and development expense associated with the Second Amended Rainier Agreement. During the nine months ended September 30, 2021, the Company recognized $6.1 million of research and development expense associated with the payment of $3.5 million and the issuance of 313,359 of its common shares as noted above. During the nine months ended September 30, 2020, the Company paid an upfront fee of $1.0 million to Rainier and recognized this as an expense as noted above. In connection with the Rainier Agreement, in March 2020, the Company was assigned all of Rainier’s rights and obligations under an exclusive license agreement between BioClin Therapeutics, Inc. and Genentech, Inc. (“Genentech”) (the “Genentech License Agreement”). Pursuant to the Genentech License Agreement, the Company has an exclusive, worldwide, sublicensable license to make, use, research, develop, sell and import certain intellectual property and technology of Genentech relating to a specified antibody and any mutant antibody thereof (the “Licensed Antibodies”), including any products that contain a Licensed Antibody as an active ingredient (the “Products”), for all human uses. Pursuant to the Genentech License Agreement, the Company is obligated to use commercially reasonable efforts to develop and commercialize at least one Product and the Company is solely responsible for the costs associated with the development, manufacturing, regulatory approval and commercialization of any Products. The manufacture of the antibody by any third-party contract manufacturing organization must be approved in advance by Genentech. Additionally, Genentech retains the right to use the Licensed Antibodies solely to research and develop molecules other than the Licensed Antibodies. Under Genentech License Agreement, the Company is obligated to make aggregate milestone payments to Genentech of up to $44.0 million upon the achievement of specified sales milestones. The Company is also obligated to pay to Genentech tiered royalties of a mid to high single-digit percentage based on annual net sales by the Company, and any of its affiliates and sublicensees, for the specified compound of antibody molecules and of a mid to high single-digit percentage based on annual net sales by the Company, and any of its affiliates and sublicensees, for any other compound containing mutant antibody molecules of the specified compound. In addition, the Company is obligated to pay to Genentech royalties of a low single-digit percentage based on quarterly net sales in any country in which the specified compound is not covered by a valid patent claim, and those sales will not be subject to the tiered royalties described above. All royalties may be reduced if the Company obtains a license under a third-party patent that includes the specified compound. Royalties will be paid by the Company on a country-by-country basis beginning upon the first commercial sale in such country until the later of (i) ten years following the date of the first commercial sale of a Product or (ii) the date the specified compound is no longer covered by an enforceable patent. Upon the expiration of the royalty term, the Company will have a fully paid-up license. The Company has the right to terminate the Genentech License Agreement upon written notice to Genentech if the Company determines in its sole discretion that development or commercialization of Products is not economically or scientifically feasible or appropriate. In addition, if the Company or Genentech fails to comply with any of its obligations or otherwise breaches the agreement, the other party may terminate the agreement. The Genentech License Agreement expires on the date on which all obligations under the agreement related to milestone payments or royalties have passed or expired. During the three and nine months ended September 30, 2021 and 2020, the Company did not make any payments to Genentech or recognize any research and development expenses under the Genentech License Agreement. Master Services and License Agreement with Yumab GmbH On May 15, 2020, the Company entered into a master services and license agreement (the “Yumab Agreement”) with Yumab GmbH (“Yumab”). Under the agreement, Yumab will assist the Company in discovering and developing certain antibodies from certain cell lines owned by Yumab. The Company plans to use the discovered antibodies in preclinical and clinical development. Under the Yumab Agreement, the Company is obligated to pay for services performed as defined in work orders under the agreement. In addition, the Company is obligated to make aggregate milestone payments to Yumab of up to $3.9 million upon the achievement of specified development and regulatory milestones. During the three and nine months ended September 30, 2021, the Company did not make any payments to Yumab or recognize any research and development expenses under the Yumab Agreement. During the three and nine months ended September 30, 2020, the Company recognized $0.2 million as research and development expense in the consolidated statements of operations and comprehensive loss under the Yumab Agreement. Collaboration Agreement and Supply Agreement with TRIUMF Innovations, Inc. On December 10, 2020, the Company entered into a Collaboration Agreement and Supply Agreement with TRIUMF Innovations Inc. and TRIUMF JV (collectively, “the TRIUMF entities”) for the development, production and supply of actinium-225 to the Company. Under the Collaboration Agreement As of September 30, 2021, the TRIUMF entities had achieved certain milestones under the Collaboration Agreement totaling $3.0 million CAD (equivalent to $2.3 million at the time of payment) which was paid during the nine months ended September 30, 2021 and are being amortized as research and development expense over the period of performance by the TRIUMF entities. During the three and nine months ended September 30, 2021, the Company recognized the amortization of $0.5 million and $1.4 million, respectively, as research and development expense under the Collaboration Agreement. As previously contemplated, on August 12, 2021, the parties amended the Collaboration Agreement in order to expand the scope of the project and the Company agreed to make an additional financial investment of up to $15.0 million CAD in connection with development of new process technology for the manufacture of actinium-225 upon the achievement of certain milestones under an amendment to the Collaboration Agreement (the “Amended Collaboration Agreement”) . In connection with the Amended Collaboration Agreement, the parties have formed a company (“NewCo”) to hold certain intellectual property derived from the collaboration. NewCo is jointly owned and managed by the Company and the TRIUMF entities and its purpose is to manufacture actinium-225 for the research, clinical and commercial needs of the Company, and in certain circumstances, other third parties. The supply of actinium-225 by NewCo to the Company shall be done under a commercial supply agreement, to be negotiated by NewCo and the Company. The Company is expected to purchase at least 50% of its annual actinium-225 requirements from NewCo , unless NewCo is unable to supply such necessary qua nt ities to the Company , in which case the Company may use other actinium-225 suppliers to meet its commercial needs . As of September 30, 2021, the TRIUMF entities had achieved certain milestones under the Amended Collaboration Agreement totaling $5.0 million CAD (equivalent to $3.9 million at the time of payment) which was paid during the three and nine months ended September 30, 2021 and is being amortized as research and development expense over the period of performance by the TRIUMF entities. During the three and nine months ended September 30, 2021, the Company did not recognize any research and development expense under the Amended Collaboration Agreement. The Company recorded $2.2 million and $2.7 million of milestone payments in prepaid expenses and other current assets and other non-current assets, respectively, as of September 30, 2021 based on its estimate of costs to be incurred over the 12 months following the balance sheet date for both the Collaboration Agreement and the Amended Collaboration Agreement. Asset Acquisition from Ipsen Pharma SAS On March 1, 2021, the Company and Ipsen Pharma SAS (“Ipsen”) announced that the parties had entered into an asset purchase agreement (the “Ipsen Agreement”) whereby the Company agreed to acquire Ipsen’s intellectual property and assets related to IPN-1087, a small molecule targeting neurotensin receptor 1 (“NTSR1”), a protein expressed on multiple solid tumor types. The Company intends to combine its expertise and proprietary TAT platform with IPN-1087 to create an alpha-emitting radiopharmaceutical targeting solid tumors expressing NTSR1. The Company and Ipsen submitted a pre-merger notification and report form with the United States Federal Trade Commission and the Antitrust Division of the United States Department of Justice in accordance with the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the “HSR Act”). The acquisition closed after completion of this antitrust review on April 1, 2021. The Company concluded to account for this purchase as an asset acquisition as substantially all of the fair value of the gross assets acquired was concentrated in a single identifiable asset, the license rights. Upon closing of the asset acquisition, the Company paid €0.6 million ($0.8 million at the date of payment) and issued an aggregate of 600,000 common shares to Ipsen under a share purchase agreement which was entered into concurrently with the Ipsen Agreement. Such common shares were issued pursuant to an exemption from the registration requirements of the Securities Act of 1933, as amended (the “Securities Act”). The Company is also obligated to pay Ipsen up to an additional €67.5 million upon the achievement of certain development and regulatory milestones; low single digit royalties on potential future net sales; and up to €350.0 million in net sales milestones, in each case, relating to products covered by the asset purchase agreement. The Company is responsible for paying to a third-party licensor up to a total of €70.0 million in development milestones for up to three indications and mid to low double-digit royalties on potential future net sales of products covered by the license agreement. During the three months ended September 30, 2021, the Company did not make any payments to Ipsen or recognize any research and development expenses under the Ipsen Agreement. During the nine months ended September 30, 2021, the Company recognized $6.4 million of research and development expense associated with the issuance of 600,000 of its common shares upon closing pursuant to the Ipsen Agreement. Additionally, during the nine months ended September 30, 2021, the Company paid $0.8 million which was recognized as research and development expense. The Ipsen Agreement includes a royalty step down whereby royalties owed to Ipsen will be reduced by certain percentages not to exceed 50%, in the aggregate, of the royalty owed under certain circumstances relating to loss of patent exclusivity, loss of regulatory exclusivity or generics entering a market. Under the asset purchase agreement Ipsen has agreed not to develop a molecule that targets NTSR1 and combines at least one NTSR1 binding moiety and a radionuclide or cytotoxic agent until the earlier of (i) the seventh anniversary of the closing date or (ii) the date of data base lock after completion of the first phase 3 clinical trial for IPN-1087. Agreement with Merck & Co. On May 5, 2021, the Company entered into an agreement with two subsidiaries of Merck & Co. (“Merck”). Pursuant to the agreement, Merck will provide to the Company, at no cost, its anti-PD-1 (programmed death receptor-1) therapy, KEYTRUDA® (pembrolizumab) to evaluate in combination with the Company’s lead candidate, FPI-1434. The planned Phase 1 combination trial will evaluate safety, tolerability and pharmacokinetics of FPI-1434 in combination with pembrolizumab and is expected to initiate approximately six to nine months after achieving the recommended Phase 2 dose in the ongoing Phase 1 study of FPI-1434 monotherapy. Under the agreement, the Company will sponsor, fund and conduct the combination trial in accordance with an agreed-upon protocol and Merck agreed to manufacture and supply its compound, at its cost and for no charge to the Company, for use in the clinical trial.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	1 1 . Income Taxes The Company is domiciled in Canada and is primarily subject to taxation in that country. During the three and nine months ended September 30, 2021, the Company recorded no income tax benefits for the net operating losses incurred or for the research and development tax credits generated in Canada in each period due to its uncertainty of realizing a benefit from those items. During the three and nine months ended September 30, 2021, the Company recorded a tax provision of less than $0.1 million and $0.1 million, respectively, related to income tax obligations of its operating company in the U.S., which typically generates a profit for tax purposes, partially offset by discrete stock compensation items arising during the period. During the three months ended September 30, 2020, the Company recorded a tax benefit of $0.2 million as a result of the Company claiming a U.S. research and development tax credit to partially offset the current U.S. tax liability. During the nine months ended September 30, 2020, the Company recorded a tax provision of less than $0.1 million primarily related to income tax obligations of its operating company in the U.S., which generates a profit for tax purposes. The Company’s tax provision and the resulting effective tax rate for interim periods is determined based upon its estimated annual effective tax rate (“AETR”), adjusted for the effect of discrete items arising in that quarter. The impact of such inclusions could result in a higher or lower effective tax rate during a particular quarter, based upon the mix and timing of actual earnings or losses versus annual projections. In each quarter, the Company updates its estimate of the annual effective tax rate, and if the estimated annual tax rate changes, a cumulative adjustment is made in that quarter. For the three and nine months ended September 30, 2021 and 2020, the Company excluded Canada and Ireland from the calculation of the AETR as the Company anticipates ordinary losses in these jurisdictions for which no tax benefit can be recognized. The Company has evaluated the positive and negative evidence bearing upon its ability to realize its deferred tax assets, which primarily consist of net operating loss carryforwards. The Company has considered its history of cumulative net losses in Canada, estimated future taxable income and prudent and feasible tax planning strategies and has concluded that it is more likely than not that the Company will not realize the benefits of its Canadian deferred tax assets. As a result, as of September 30, 2021 and December 31, 2020, the Company has recorded a full valuation allowance against its net deferred tax assets in Canada. As a result of the decision to liquidate the Irish subsidiary, the Irish deferred tax assets were reduced to zero as of September 30, 2021 and December 31, 2020. The liquidation and dissolution of the Company's Irish subsidiary was completed in September 2021.

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss per Share	1 2 . Net Loss per Share Net Loss per Share Attributable to Common Shareholders Basic and diluted net loss per share attributable to common shareholders was calculated as follows (in thousands, except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Numerator: Net loss $ (19,429 ) $ (9,993 ) $ (63,811 ) $ (64,948 ) Dividends paid to preferred shareholders in the form of warrants issued — — — (1,382 ) Net loss attributable to common shareholders $ (19,429 ) $ (9,993 ) $ (63,811 ) $ (66,330 ) Denominator: Weighted-average common shares outstanding—basic and diluted 43,022,762 41,682,797 42,441,091 15,422,375 Net loss per share attributable to common shareholders —basic and diluted $ (0.45 ) $ (0.24 ) $ (1.50 ) $ (4.30 ) The Company’s potentially dilutive securities, which include stock options, convertible preferred shares, preferred exchangeable shares and common share warrants, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common shareholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common shareholders for the periods indicated because including them would have had an anti-dilutive effect: Nine Months Ended September 30, 2021 2020 Options to purchase common shares 7,649,288 5,266,466 Convertible preferred shares (as converted to common shares) — — Preferred exchangeable shares (as converted to convertible preferred shares and then to common shares) — — Warrants to purchase common shares 651,816 651,816 8,301,104 5,918,282

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Leases	1 3 . Leases In January 2018, the Company entered into an operating lease for office space in Boston, Massachusetts, which was to expire in July 2023 In August 2018, the Company entered into an operating lease for office space in Hamilton, Ontario. This lease was amended in September 2020 (“New Lease Commencement Date”) and expires in August 2030 five-year In October 2019, the Company entered into an operating lease for office space in Boston, Massachusetts, which expires February 2026 On March 16, 2021, the Company entered into an amendment to expand the area under lease (“Expansion Premises”) and extend the term of the premises currently under lease (“Original Premises”) to align with the lease end date for the Expansion Premises. The additional rent for the Expansion Premises was determined to be commensurate with the additional right-of-use and is accounted for as a new operating lease that was recognized on the Company’s balance sheet as of September 30, 2021 since the Company was able to access the Expansion Premises. The Company expects to make certain improvements to the Expansion Premises, for which the landlord will provide the Company an allowance of up to $0.2 million. The Company currently expects the rent for the Expansion Space, which is under construction, to commence on January 1, 2022. The Company currently expects the lease end date for the Original Premises and the Expansion Premises lease to be April 30, 2027, with no option to extend the lease term. The lease modification for the extension of the Original Premises and the recognition of the Expansion Premises resulted in increases to the Company’s right-of-use asset balance, which was obtained in exchange for operating lease liabilities, of $0.9 million and $1.2 million, respectively. On June 1, 2021, the Company entered into a lease for a manufacturing facility in Hamilton, Ontario. The Company currently expects the rent for the manufacturing facility, which is under construction, to commence in October 2022, approximately two months after the anticipated delivery date of the premises. The Company currently expects the lease end date for the manufacturing facility to be in September 2037 five-year The components of operating lease cost, which are included within operating expenses in the accompanying condensed consolidated statements of operations and comprehensive loss, are as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2021 Operating lease cost $ 365 $ 1,032 Variable lease cost 4 20 Total lease cost $ 369 $ 1,052 The following table summarizes supplemental information for the Company’s operating leases: As of September 30, 2021 Weighted-average remaining lease term (in years) 5.5 Weighted average discount rate 4.9 % Cash paid for amounts included in the measurement of lease liabilities $ 858 As of September 30, 2021, the future maturities of operating lease liabilities are as follows (in thousands): Year Ending December 31, 2021 (three months) $ 292 2022 1,427 2023 1,463 2024 1,499 2025 1,537 Thereafter 1,894 Total lease payments $ 8,112 Less: imputed interest (1,002 ) Total lease liabilities $ 7,110 In accordance with ASC 840, rent expense was $0.3 million and $0.8 million for the three and nine months ended September 30, 2020, respectively. Future minimum lease payments due under operating leases as of December 31, 2020 were as follows (in thousands): Year Ending December 31, 2021 $ 1,127 2022 1,158 2023 1,190 2024 1,221 2025 1,253 Thereafter 361 Total $ 6,310

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	1 4 . Commitments and Contingencies Manufacturing Commitments In January 2019, and as amended in September 2020, the Company entered into an agreement with CPDC, a related party (see Note 15), to manufacture clinical trial materials. As of September 30, 2021, the Company had non-cancelable minimum purchase commitments under the agreement totaling $0.4 million over the following twelve months. In May 2019, the Company entered into an agreement with a third-party contract manufacturing organization to manufacture clinical trial materials. As of September 30, 2021, the Company had non-cancelable minimum purchase commitments under the agreement totaling $0.8 million over the following twelve months. Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and certain of its executive officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not currently aware of any indemnification claims and has not accrued any liabilities related to such obligations in its condensed consolidated financial statements as of September 30, 2021 or December 31, 2020. Legal Proceedings The Company is not a party to any litigation and does not have contingency reserves established for any litigation liabilities. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses as incurred the costs related to such legal proceedings.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	1 5 . Related Party Transactions The Company’s chief executive officer, founder and member of the board of directors, John Valliant, Ph.D., is a member of the board of directors at CPDC. The Company has entered into license agreements with CPDC (see Note 10). In addition, the Company has entered into a Master Services Agreement and a Supply Agreement with CPDC, under which CPDC provides services to the Company related to preclinical and manufacturing services, administrative support services and access to laboratory facilities. In connection with the Supply Agreement, the Company is obligated to pay CPDC an amount of $0.2 million per quarter, or $0.8 million in the aggregate per year, plus fees for materials, packaging and distribution of products supplied to the Company, unless the agreement is terminated by the Company. The Company recognized expenses in connection with the services performed in the normal course of business under the Master Services Agreement and the Supply Agreement in the condensed consolidated statements of operations and comprehensive loss as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development expenses $ 570 $ 141 $ 1,226 $ 780 General and administrative expenses 10 23 42 50 $ 580 $ 164 $ 1,268 $ 830 During the three and nine months ended September 30, 2021, the Company made payments to CPDC in connection with the services described above of $0.5 million and $1.4 million, respectively. During the three and nine months ended September 30, 2020, the Company made payments to CPDC in connection with the services described above of $0.2 million and $1.0 million, respectively. Amounts due to CPDC by the Company in connection with the services described above totaled $0.3 million as of September 30, 2021 and December 31, 2020 which amounts were included in accounts payable and accrued expenses on the condensed consolidated balance sheets. In addition to costs incurred in connection with the services described above, the Company also reimbursed CPDC for purchases on the Company’s behalf from parties with which the Company did not have an account. During the three and nine months ended September 30, 2021, the Company made payments to CPDC of less than $0.1 million and $0.2 million, respectively, for reimbursement of these pass-through costs. During the three and nine months ended September 30, 2020, the Company made payments to CPDC of less than $0.1 million and $0.1 million, respectively, for reimbursement of these pass-through costs. In connection with the Company entering into a lease for a manufacturing facility in Hamilton, Ontario (see Note 13), the Company entered into an agreement with CPDC for services relating to certain aspects of the validation of the manufacturing facility which is currently under construction. During the nine months ended September 30, 2021, the Company paid $3.0 million CAD (equivalent to $2.5 million at the time of payment) which was recorded as research and development expense.

Geographical Information

Geographical Information	9 Months Ended
	Sep. 30, 2021
Geographic Areas Long Lived Assets [Abstract]
Geographical Information	1 6 . Geographical Information The Company has operating companies in the United States and Canada and a non-operating company in Ireland. Information about the Company’s long-lived assets, consisting solely of property and equipment, net, by geographic region was as follows (in thousands): September 30, 2021 December 31, 2020 United States $ 83 $ 103 Canada 2,377 1,864 $ 2,460 $ 1,967

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Reverse Share Split	Reverse Share Split On June 19, 2020, the Company effected a one-for-5.339 reverse share split of its issued and outstanding common shares and a proportional adjustment to the existing conversion ratios for each class of the Company’s Preferred Shares (see Note 8) and Preferred Exchangeable Shares (see Note 8). Accordingly, all share and per share amounts for all periods presented in the accompanying condensed consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse share split and adjustment of the preferred share conversion ratios.
Initial Public Offering	Initial Public Offering On June 25, 2020, the Company completed an initial public offering (“IPO”) of its common shares and issued and sold 12,500,000 common shares at a public offering price of $17.00 per share, resulting in net proceeds of $193.1 million after deducting underwriting fees, and after deducting offering costs. Upon closing of the IPO, the Company’s outstanding preferred exchangeable shares automatically converted into convertible preferred shares then the outstanding convertible preferred shares automatically converted into shares of common shares (see Note 8). Upon conversion of the convertible preferred shares, the Company reclassified the carrying value of the convertible preferred shares to common shares and additional paid-in capital. In addition, the warrants to purchase the Company’s Series B convertible preferred shares and warrants to purchase preferred exchangeable shares of the Company’s Irish subsidiary were converted into warrants to purchase the Company’s common shares upon the closing of the IPO. As a result, the warrant liability was remeasured a final time on the closing date of the IPO and reclassified to shareholders’ equity (deficit). In connection with the IPO on June 25, 2020, the Company filed an amended and restated articles of the corporation under laws governed by the Canada Business Corporations Act
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. Since inception, the Company has funded its operations primarily with proceeds from sales of its convertible preferred shares, including borrowings under a convertible promissory note, which converted into convertible preferred shares, proceeds from sales of its Irish subsidiary’s preferred exchangeable shares, and most recently with the proceeds from the IPO completed in June 2020. 19.4 63.8 10.0 $ 64.9 September 30, 2021 177.0
Impact of the COVID-19 Pandemic	Impact of the COVID-19 Pandemic The COVID-19 pandemic, which began in December 2019 and has spread worldwide, has caused many governments to implement measures to slow the spread of the outbreak through quarantines, travel restrictions, heightened border security and other measures. The impact of this pandemic has been, and will likely continue to be, extensive in many aspects of society, which has resulted, and will likely continue to result, in significant disruptions to the global economy as well as businesses and capital markets around the world. The future progression of the pandemic and its effects on the Company’s business and operations are uncertain. In response to public health directives and orders and to help minimize the risk of the virus to employees, the Company has taken precautionary measures, including implementing work-from-home policies for certain employees. The impact of the virus and variants thereof, including work-from-home policies, may negatively impact productivity, disrupt the Company’s business, and delay its preclinical research and clinical trial activities and its development program timelines, the magnitude of which will depend, in part, on the length and severity of the restrictions and other limitations on the Company’s ability to conduct its business in the ordinary course. Specifically, the Company has experienced material delays in patient recruitment and enrollment in its ongoing Phase 1 clinical trial of FPI-1434 as a result of continued resourcing issues related to COVID-19 at trial sites and potentially due to concerns among patients about participating in clinical trials during a public health emergency. The Company may not be able to enroll additional patient cohorts on its planned timeline due to disruptions at its clinical trial sites and is unable to predict how the COVID-19 pandemic may affect its ability to successfully progress its clinical programs in the future. Other impacts to the Company’s business may include temporary closures of its suppliers or other third parties upon whom the Company relies and disruptions or restrictions on its employees’ ability to travel. Any prolonged material disruption to the Company’s employees, suppliers or other third parties upon whom the Company relies could adversely impact the Company’s preclinical research and clinical trial activities, financial condition and results of operations, including its ability to obtain financing. The Company is monitoring the potential impact of the COVID-19 pandemic, including variants thereof, on its business and condensed consolidated financial statements. To date, the Company has not incurred impairment losses in the carrying values of its assets as a result of the pandemic and it is not aware of any specific related event or circumstance that would require it to revise its estimates reflected in these condensed consolidated financial statements.
Use of Estimates	Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses, the valuations of common shares, preferred share tranche rights and preferred share warrants prior to the closing of the IPO, valuations of share-based awards and revenue recognition. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ from those estimates or assumptions.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of September 30, 2021, the condensed consolidated statement of operations and comprehensive loss, and the condensed consolidated statement of non-controlling interest, convertible preferred shares and shareholders’ equity (deficit) for the three and nine months ended September 30, 2021 and 2020, and the condensed consolidated statement of cash flows for the nine months ended September 30, 2021 and 2020 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2021 and the results of its operations for three and nine months ended September 30, 2021 and 2020 and its cash flows for the nine months ended September 30, 2021 and 2020. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2021 and 2020 are also unaudited. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of results to be expected for the year ending December 31, 2021, any other interim periods, or any future year or period. The accompanying balance sheet as of December 31, 2020 has been derived from the Company’s audited financial statements for the year ended December 31, 2020. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. These unaudited interim condensed consolidated financial statements should be read in conjunction with the audited annual consolidated financial statements as of December 31, 2020 included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 25, 2021.
Foreign Currency and Currency Translation	Foreign Currency and Currency Translation The reporting currency of the Company is the U.S. dollar. The functional currency of the Company’s operating company in Canada, operating company in the U.S. and non-operating company in Ireland is also the U.S. dollar. As a result, the Company records no cumulative translation adjustments related to translation of unrealized foreign exchange gains or losses. For the remeasurement of local currencies to the U.S. dollar functional currency of the Canadian and Irish entities, assets and liabilities are translated into U.S. dollars at the exchange rate in effect on the balance sheet date, and income items and expenses are translated into U.S. dollars at the average exchange rate in effect during the period. Resulting transaction gains (losses) are included in other income (expense), net in the consolidated statements of operations and comprehensive loss, as incurred. Adjustments that arise from exchange rate changes on transactions denominated in a currency other than the local currency are included in other income (expense), net in the consolidated statements of operations and comprehensive loss, as incurred. During the three and nine months ended September 30, 2021, the Company recorded less than ($0.1) million and $0.1 million, respectively, of foreign currency gains (losses) in the condensed consolidated statements of operations and comprehensive loss. During the three and nine months ended September 30, 2020, the Company recorded less than ($0.1)
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents consist of standard checking accounts, money market accounts, and all highly liquid investments with an original maturity of three months or less at the date of purchase. As of September 30, 2021 and December 31, 2020, the Company was required to maintain separate cash balances of $0.3 million to collateralize corporate credit cards with a bank, which was classified as restricted cash, current, on its condensed consolidated balance sheets. The Company also maintained a $0.1 million guaranteed investment certificate to fulfill certain contractual obligations which was classified as restricted cash, current, as of September 30, 2021 and December 31, 2020. In connection with the Company’s lease agreement entered into in October 2019 (see Note 13), the Company maintains a letter of credit of $1.5 million for the benefit of the landlord. As of September 30, 2021, $0.3 million and $1.2 million of the underlying cash balance collateralizing this letter of credit was classified as restricted cash, current and non-current, respectively, on the Company’s condensed consolidated balance sheets based on the release date of the restrictions of this cash. As of December 31, 2020, the entire underlying cash balance collateralizing this letter of credit was classified as restricted cash, non-current, on the Company’s condensed consolidated balance sheets. As of September 30, 2021 and December 31, 2020 , the cash , cash equivalents and restricted cash of $ 40.3 million and $ million, respectively, presented in the condensed consolidated statements of cash flows included cash and cash equivalents of $ 38.4 million and $ million, respectively, and restricted cash of $ million for both periods .
Investments	Investments The Company determines the appropriate classification of its investments in debt securities at the time of purchase and re-evaluates such determination at each balance sheet date. The Company classifies its investments as current or non-current based on each instrument’s underlying maturity date. Investments with original maturities of greater than three months and less than twelve months are classified as current and are included in short-term investments in the condensed consolidated balance sheets. Investments with remaining maturities greater than one year from the balance sheet date are classified as non-current and are included in long-term investments in the condensed consolidated balance sheets. The Company’s investments are classified as available-for-sale, are reported at fair value and consist of U.S. government agency securities, corporate bonds, and commercial paper. Unrealized gains and losses are included in other comprehensive income (loss) as a component of shareholders’ equity (deficit) until realized. Amortization and accretion of premiums and discounts are recorded in interest income (expense). Realized gains and losses on debt securities are included in other income (expense), net. If any adjustment to fair value reflects a decline in value of the investment, the Company considers all available evidence to evaluate the extent to which the decline is other than temporary and, if so, marks the investment to market on the Company’s condensed consolidated statements of operations and comprehensive loss.
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of an equity financing, these costs are recorded as a reduction of the proceeds from the offering, either as a reduction to the carrying value of the preferred exchangeable shares or convertible preferred shares or in shareholders’ equity (deficit) as a reduction of additional paid-in capital generated as a result of the offering. Should an in-process equity financing be abandoned, the deferred offering costs would be expensed immediately as a charge to operating expenses in the consolidated statements of operations and comprehensive loss. The Company recorded $0.3 million of deferred offering costs as of September 30, 2021 in other non-current assets and did not record any deferred offering costs as of December 31, 2020.
Collaborative Arrangements	Collaborative Arrangements The Company considers the nature and contractual terms of arrangements and assesses whether an arrangement involves a joint operating activity pursuant to which the Company is an active participant and is exposed to significant risks and rewards dependent on the commercial success of the activity. If the Company is an active participant and is exposed to significant risks and rewards dependent on the commercial success of the activity, the Company accounts for such arrangement as a collaborative arrangement under ASC 808, Collaborative Arrangements For arrangements determined to be within the scope of ASC 808 where a collaborative partner is not a customer for certain research and development activities, the Company accounts for payments received for the reimbursement of research and development costs as a contra-expense in the period such expenses are incurred. This reflects the joint risk sharing nature of these activities within a collaborative arrangement. The Company classifies payments owed or receivables recorded as other current liabilities or prepaid expenses and other current assets, respectively, in the Company’s consolidated balance sheets. If payments from the collaborative partner to the Company represent consideration from a customer in exchange for distinct goods and services provided, then the Company accounts for those payments within the scope of ASC 606, Revenue from Contracts with Customers
Revenue from Contracts with Customers	Revenue from Contracts with Customers In accordance with ASC 606, the Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, it performs the following five steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations within the contract and (v) recognize revenue when (or as) the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when it determines that it is probable it will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within the contract to determine whether each promised good or service is a performance obligation. The promised goods or services in the Company’s arrangements typically consist of a license to the Company’s intellectual property and/or research and development services. The Company may provide customers with options to additional items in such arrangements, which are accounted for separately when the customer elects to exercise such options, unless the option provides a material right to the customer. Performance obligations are promises in a contract to transfer a distinct good or service to the customer that (i) the customer can benefit from on its own or together with other readily available resources, and (ii) is separately identifiable from other promises in the contract. Goods or services that are not individually distinct performance obligations are combined with other promised goods or services until such combined group of promises meet the requirements of a performance obligation. The Company determines transaction price based on the amount of consideration the Company expects to receive for transferring the promised goods or services in the contract. Consideration may be fixed, variable, or a combination of both. At contract inception for arrangements that include variable consideration, the Company estimates the probability and extent of consideration it expects to receive under the contract utilizing either the most likely amount method or expected amount method, whichever best estimates the amount expected to be received. The Company then considers any constraints on the variable consideration and includes in the transaction price variable consideration to the extent it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. The Company then allocates the transaction price to each performance obligation based on the relative standalone selling price and recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to the customer and the performance obligation is satisfied. For performance obligations which consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The Company records amounts as accounts receivable when the right to consideration is deemed unconditional. Amounts received, or that are unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract are recognized as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as the current portion of deferred revenue. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. The Company’s revenue generating arrangements typically include upfront license fees, milestone payments and/or royalties. If a license is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from nonrefundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. At the inception of an agreement that includes research and development milestone payments, the Company evaluates each milestone to determine when and how much of the milestone to include in the transaction price. The Company first estimates the amount of the milestone payment that the Company could receive using either the expected value or the most likely amount approach. The Company primarily uses the most likely amount approach as this approach is generally most predictive for milestone payments with a binary outcome. Then, the Company considers whether any portion of the estimated amount is subject to the variable consideration constraint (that is, whether it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty). The Company updates the estimate of variable consideration included in the transaction price at each reporting date which includes updating the assessment of the likely amount of consideration and the application of the constraint to reflect current facts and circumstances. For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). For the three and nine months ended September 30, 2021, the Company recorded $0.3 million and $0.8 million, respectively, of revenue under collaboration agreements. Please refer to Note 3, “Collaboration Agreement” for additional details regarding revenue recognition under the AstraZeneca Agreement.
Business Combinations	Business Combinations In determining whether an acquisition should be accounted for as a business combination or asset acquisition, the Company first determines whether substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets. If this is the case, the single identifiable asset or the group of similar assets is not deemed to be a business, and is instead deemed to be an asset. If this is not the case, the Company then further evaluates whether the single identifiable asset or group of similar identifiable assets and activities includes, at a minimum, an input and a substantive process that together significantly contribute to the ability to create outputs. If so, the Company concludes that the single identifiable asset or group of similar identifiable assets and activities is a business. The Company accounts for business combinations using the acquisition method of accounting. Application of this method of accounting requires that (i) identifiable assets acquired (including identifiable intangible assets) and liabilities assumed generally be measured and recognized at fair value as of the acquisition date and (ii) the excess of the purchase price over the net fair value of identifiable assets acquired and liabilities assumed be recognized as goodwill, which is not amortized for accounting purposes but is subject to testing for impairment at least annually. Acquired in-process research and development (“IPR&D”) is recognized at fair value and initially characterized as an indefinite-lived intangible asset, irrespective of whether the acquired IPR&D has an alternative future use. Transaction costs related to business combinations are expensed as incurred. Determining the fair value of assets acquired and liabilities assumed in a business combination requires management to use significant judgment and estimates, especially with respect to intangible assets. During the measurement period, which extends no later than one year from the acquisition date, the Company may record certain adjustments to the carrying value of the assets acquired and liabilities assumed with the corresponding offset to goodwill. After the measurement period, all adjustments are recorded in the consolidated statements of operations as operating expenses or income. To date, the Company has not recorded any acquisitions as a business combination.
Asset Acquisitions	Asset Acquisitions The Company measures and recognizes asset acquisitions that are not deemed to be business combinations based on the cost to acquire the assets, which includes transaction costs. Goodwill is not recognized in asset acquisitions. In an asset acquisition, the cost allocated to acquire IPR&D with no alternative future use is charged to expense at the acquisition date. Contingent consideration in asset acquisitions payable in the form of cash is recognized when payment becomes probable and reasonably estimable, unless the contingent consideration meets the definition of a derivative, in which case the amount becomes part of the asset acquisition cost when acquired. Contingent consideration payable in the form of a fixed number of the Company’s own shares is measured at fair value as of the acquisition date and recognized when the issuance of the shares becomes probable. Upon recognition of the contingent consideration payment, the amount is included in the cost of the acquired asset or group of assets, or, if related to IPR&D with no alternative future use, charged to expense.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. Prior to the settlement of the Company’s preferred share tranche right liability and prior to the conversion of the Company’s preferred share warrant liability , these instruments were carried at fair value, determined according to Level 3 inputs in the fair value hierarchy described above (see Note 4 ). The Company’s cash equivalents and investments are carried at fair value, determined according to the fair value hierarchy described above (see Note 4 ). The carrying values of the Company’s amounts due for refundable investment tax credits and Canadian harmonized sales tax, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these liabilities.
Preferred Share Tranche Right Liability and Preferred Share Warrant Liability	Preferred Share Tranche Right Liability The subscription agreements for the Company’s Class B convertible preferred shares (see Note 8) and its Irish subsidiary’s Class B preferred exchangeable shares (see Note 8) provided investors the right, or obligated investors, to participate in subsequent offerings of Class B convertible preferred shares or Class B preferred exchangeable shares together with Class B special voting shares in the event that specified development or regulatory milestones were achieved (the “Class B preferred share tranche right liability”). The Company classified these preferred share tranche rights as a liability on its consolidated balance sheets as each preferred share tranche right was a freestanding financial instrument that may have required the Company to transfer assets upon the achievement of specified milestone events. Each preferred share tranche right liability was initially recorded at fair value upon the date of issuance of each preferred share tranche right and was subsequently remeasured to fair value at each reporting date. Changes in the fair value of the preferred share tranche right liability were recognized as a component of other income (expense) in the consolidated statement of operations and comprehensive loss. Changes in the fair value of the preferred share tranche right liability were recognized until the respective preferred share tranche right was settled upon achievement of the specified milestones or it expired. On May 15, 2020, the Company achieved the specified regulatory milestone associated with the Class B preferred share tranche right (see Note 8), which triggered the requirement of the Class B shareholders to participate in the Milestone Financing. Upon closing of the Milestone Financing on June 2, 2020, the Company issued and sold 36,806,039 Class B preferred shares at a price of $1.5154 per share and 4,437,189 Class B special voting shares at a price of $0.000001 per share and the Company’s Irish subsidiary issued and sold 4,437,189 Class B preferred exchangeable shares at a price of $1.5154 per share, for aggregate gross proceeds of $62.5 million. The Class B preferred share tranche right liability (see Note 8) was settled in connection with the achievement of the regulatory milestone associated with the Class B preferred share tranche right. Specifically, the fair value of the Class B preferred share tranche right liability was remeasured for the last time as of the Milestone Financing closing date, resulting in the Company recognizing a loss in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2020 of $32.7 million for the change in the fair value of the tranche right liability between December 31, 2019 and June 2, 2020. Immediately thereafter, the balance of the Class B preferred share tranche right liability of $39.6 million was reclassified to Class B convertible preferred shares in an amount of $35.3 million and to non-controlling interest in the Company’s Irish subsidiary in an amount of $4.3 million on the consolidated balance sheet. For the nine months ended September 30, 2020, the Company recognized a loss of $32.7 million in the condensed consolidated statement of operations and comprehensive loss for the change in the fair value of the tranche right liability. Preferred Share Warrant Liability The Company classified warrants to purchase its convertible preferred shares and warrants to purchase preferred exchangeable shares of the Company’s Irish subsidiary as a liability on its consolidated balance sheets as these warrants were freestanding financial instruments that may have required the Company to transfer assets upon exercise (see Note 8). The preferred share warrant liability, which consisted of warrants to purchase Class B convertible preferred shares of the Company and warrants to purchase Class B preferred exchangeable shares of the Company’s Irish subsidiary, were initially recorded at fair value upon the date of issuance of each warrant and were subsequently remeasured to fair value at each reporting date. Changes in the fair value of the preferred share warrant liability were recognized as a component of other income (expense) in the consolidated statement of operations and comprehensive loss. Changes in the fair value of the preferred share warrant liability were recognized until each respective warrant was exercised, expired or qualified for equity classification. Upon the closing of the IPO, the warrants to purchase its convertible preferred shares and warrants to purchase preferred exchangeable shares of the Company’s Irish subsidiary were converted into warrants to purchase shares of the Company’s common shares. As a result, the warrant liability was remeasured a final time on the closing date of the IPO and reclassified to shareholders’ equity (deficit) as the warrants qualify for equity classification.
Leases	Leases Prior to January 1, 2021, the Company accounted for leases in accordance with ASC 840, Leases inclusive of rent escalation, holidays and lease incentives, on a straight-line basis over the lease term. The difference between rent expense recorded and the amount paid was charged to deferred rent. The Company presented lease incentives as deferred rent and amortized the incentives as a reduction to rent expense on a straight-line basis over the lease term. The Company classified deferred rent as current and noncurrent liabilities based on the portion of the deferred rent that was scheduled to mature within the proceeding twelve months. Effective January 1, 2021, the Company accounts for leases in accordance with ASC 842, Leases A right-of-use asset represents the economic benefit conveyed to the Company by the right to use the underlying asset over the lease term. A lease liability represents the obligation to make lease payments arising from the lease. The Company records amortization of operating right-of-use assets and accretion of lease liabilities as a single lease cost on a straight-line basis over the lease term. The Company elected the practical expedient to not separate lease and non-lease components and therefore measures each lease payment as the total of the fixed lease and associated non-lease components. Lease liabilities are measured at the lease commencement date and calculated as the present value of the future lease payments in the contract using the rate implicit in the contract, when available. If an implicit rate is not readily determinable, the Company uses its incremental borrowing rate measured as the rate at which the Company could borrow, on a fully collateralized basis, a commensurate loan in the same currency over a period consistent with the lease term at the commencement date. Right-of-use assets are measured as the lease liability plus initial direct costs and prepaid lease payments, less lease incentives granted by the lessor. The lease term is measured as the noncancelable period in the contract, adjusted for any options to extend or terminate when it is reasonably certain the Company will extend the lease term via such options based on an assessment of economic factors present as of the lease commencement date. The Company elected the practical expedient to not recognize leases with a lease term of twelve months or less. The Company assesses its right-of-use assets for impairment consistent with the assessment performed for long-lived assets used in operations. If an impairment is recognized on operating lease right-of-use assets, the lease liability continues to be recognized using the same effective interest method as before the impairment and the operating lease right-of-use asset is amortized over the remaining term of the lease on a straight-line basis. The Company’s operating leases are presented in the condensed consolidated balance sheet as operating lease right-of-use assets, classified as noncurrent assets, and operating lease liabilities, classified as current and noncurrent liabilities based on the discounted lease payments to be made within the proceeding twelve months. Variable costs associated with a lease, such as maintenance and utilities, are not included in the measurement of the lease liabilities and right-of-use assets but rather are expensed when the events determining the amount of variable consideration to be paid have occurred.
Research, Development and Manufacturing Contract Costs and Accruals	Research, Development and Manufacturing Contract Costs and Accruals The Company has entered into various research, development and manufacturing contracts with research institutions and other companies. These agreements are generally cancelable, and related costs are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research, development and manufacturing costs. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of outstanding obligations to those third parties as of period end. Any accrual estimates are based on a number of factors, including the Company’s knowledge of the progress towards completion of the research, development and manufacturing activities, invoicing to date under the contracts, communication from the research institutions and other companies of any actual costs incurred during the period that have not yet been invoiced and the costs included in the contracts. Significant judgments and estimates may be made in determining the accrued balances at the end of any reporting period. Actual results could differ from the estimates made by the Company. The historical accrual estimates made by the Company have not been materially different from the actual costs.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss as well as other changes in shareholders’ equity (deficit) that result from transactions and economic events other than those with shareholders. For the three and nine months ended September 30, 2021 and 2020, unrealized gains and losses on investments are included in other comprehensive income (loss) as a component of shareholders’ equity (deficit) until realized.
Net Loss per Share	Net Loss per Share The Company follows the two-class method when computing net income (loss) per share as the Company has issued shares that meet the definition of participating securities. The two-class method determines net income (loss) per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common shareholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. Basic net income (loss) per share attributable to common shareholders is computed by dividing the net income (loss) attributable to common shareholders by the weighted-average number of common shares outstanding for the period. Diluted net income (loss) attributable to common shareholders is computed by adjusting net income (loss) attributable to common shareholders to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net income (loss) per share attributable to common shareholders is computed by dividing the diluted net income (loss) attributable to common shareholders by the weighted-average number of common shares outstanding for the period, including potential dilutive common shares. For purpose of this calculation, outstanding stock options, warrants and convertible preferred shares are considered potential dilutive common shares. The Company’s convertible preferred shares contractually entitle the holders of such shares to participate in dividends but do not contractually require the holders of such shares to participate in losses of the Company. Accordingly, in periods in which the Company reports a net loss attributable to common shareholders, such losses are not allocated to such participating securities. In periods in which the Company reported a net loss attributable to common shareholders, diluted net loss per share attributable to common shareholders is the same as basic net loss per share attributable to common shareholders, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The Company reported a net loss attributable to common shareholders for the three and nine months ended September 30, 2021 and 2020.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), as subsequently amended, which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors), and replaces the existing guidance in ASC 840, Leases The Company early adopted the new leasing standard effective January 1, 2021, using the alternative modified retrospective transition approach applied to leases existing as of January 1, 2021. As a result, prior periods are presented in accordance with the previous guidance in ASC 840. The Company has elected to apply the package of practical expedients requiring no reassessment of whether any expired or existing contracts are or contain leases, the lease classification of any expired or existing leases, or the capitalization of initial direct costs for any existing leases. Additionally, the Company has elected not to separate lease and non-lease components and not to recognize leases with an initial term of twelve months or less. The cumulative effect of the adoption of ASC 842 on the Company’s consolidated balance sheets as of January 1, 2021 was as follows (in thousands): Balance as of Impact of Balance as of December 31, 2020 Adoption January 1, 2021 Prepaid expenses and other current assets $ 5,340 $ (26 ) $ 5,314 Operating lease right-of-use assets $ — $ 5,664 $ 5,664 Total assets $ 310,676 $ 5,638 $ 316,314 Operating lease liabilities $ — $ 959 $ 959 Deferred rent, net of current portion $ 11 $ (11 ) $ — Operating lease liabilities, net of current portion $ — $ 4,690 $ 4,690 Total liabilities $ 16,163 $ 5,638 $ 21,801 The adoption of ASC 842 did not have a material impact on the Company’s condensed consolidated statements of operations and comprehensive loss, statements of non-controlling interest, convertible preferred shares and shareholders’ equity (deficit) or statements of cash flows as of January 1, 2021. In December 2019, the FASB issued ASU No. 2019-12 , Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements The Company qualifies as “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has elected to “opt in” to the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and nonpublic companies, the Company will adopt the new or revised standard at the time nonpublic companies adopt the new or revised standard and will do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company. The Company may choose to early adopt any new or revised accounting standards whenever such early adoption is permitted for private companies. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments—Credit Losses Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Schedule of Cumulative Effect of Adoption of ASC 842 on Company's Consolidated Balance Sheets	The cumulative effect of the adoption of ASC 842 on the Company’s consolidated balance sheets as of January 1, 2021 was as follows (in thousands): Balance as of Impact of Balance as of December 31, 2020 Adoption January 1, 2021 Prepaid expenses and other current assets $ 5,340 $ (26 ) $ 5,314 Operating lease right-of-use assets $ — $ 5,664 $ 5,664 Total assets $ 310,676 $ 5,638 $ 316,314 Operating lease liabilities $ — $ 959 $ 959 Deferred rent, net of current portion $ 11 $ (11 ) $ — Operating lease liabilities, net of current portion $ — $ 4,690 $ 4,690 Total liabilities $ 16,163 $ 5,638 $ 21,801

Collaboration Agreement (Tables

Collaboration Agreement (Tables)	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Changes in the Contract Assets and Liabilities	The following table presents changes in the Company’s contract assets and liabilities for the nine months ended September 30, 2021 (in thousands): Balance as of Balance as of December 31, 2020 Additions Deductions September 30, 2021 Contract assets: Accounts receivable $ — $ 300 $ — $ 300 Contract liabilities: Deferred revenue $ 5,000 $ — $ (546 ) $ 4,454
Schedule of Revenue Recognized	During the three and nine months ended September 30, 2021 and 2020, the Company recognized the following revenue (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Revenue recognized in the period from: Amounts included in deferred revenue at the beginning of the period $ 146 $ — $ 546 $ —

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables present information about the Company’s financial assets and liabilities that are measured at fair value on a recurring basis and indicates the level of the fair value hierarchy used to determine such fair values (in thousands): Fair Value Measurements as of September 30, 2021 Using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 12,040 $ — $ — $ 12,040 U.S. Government agencies — 10,949 — 10,949 Investments: Commercial paper — 24,788 — 24,788 Corporate bonds — 28,365 — 28,365 Municipal bonds — 17,021 — 17,021 Canadian Government agencies — 5,682 — 5,682 U.S. Government agencies — 123,936 — 123,936 $ 12,040 $ 210,741 $ — $ 222,781 Fair Value Measurements as of December 31, 2020 Using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 19,277 $ — $ — $ 19,277 Commercial paper — 1,000 — 1,000 Corporate bonds — 950 — 950 Canadian Government agencies — 2,347 — 2,347 Investments: Commercial paper — 34,471 — 34,471 Corporate bonds — 26,857 — 26,857 Municipal bonds — 1,090 — 1,090 Canadian Government agencies — 9,457 — 9,457 U.S. Government agencies — 137,089 — 137,089 $ 19,277 $ 213,261 $ — $ 232,538

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2021
Investments Debt And Equity Securities [Abstract]
Schedule of Investments	Investments consisted of the following (in thousands): September 30, 2021 Amortized Cost Fair Value Due within one year or less $ 154,155 $ 154,238 Due after one year through three years 45,574 45,554 $ 199,729 $ 199,792 December 31, 2020 Amortized Cost Fair Value Due within one year or less $ 131,857 $ 131,882 Due after one year through three years 77,063 77,082 $ 208,920 $ 208,964
Amortized Cost and Estimated Fair Value of Investments by Contractual Maturity	As of September 30, 2021, the amortized cost and estimated fair value of investments, by contractual maturity, was as follows (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Current Non-Current Commercial paper $ 24,787 $ 1 $ — $ 24,788 $ 24,788 $ — Corporate bonds 28,327 43 (5 ) 28,365 23,856 4,509 Municipal bonds 17,023 2 (4 ) 17,021 14,766 2,255 Canadian Government agencies 5,637 45 — 5,682 4,578 1,104 U.S. Government agencies 123,955 10 (29 ) 123,936 86,250 37,686 $ 199,729 $ 101 $ (38 ) $ 199,792 $ 154,238 $ 45,554 As of December 31, 2020, the amortized cost and estimated fair value of investments, by contractual maturity, was as follows (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Current Non-Current Commercial paper $ 34,474 $ 1 $ (4 ) $ 34,471 $ 34,471 $ — Corporate bonds 26,855 22 (20 ) 26,857 9,446 17,411 Municipal bonds 1,090 — — 1,090 1,090 — Canadian Government agencies 9,405 52 — 9,457 6,154 3,303 U.S. Government agencies 137,096 8 (15 ) 137,089 80,721 56,368 $ 208,920 $ 83 $ (39 ) $ 208,964 $ 131,882 $ 77,082

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	9 Months Ended
	Sep. 30, 2021
Prepaid Expense And Other Assets Current [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): September 30, 2021 December 31, 2020 Prepaid external research and development expenses $ 3,446 $ 1,606 Prepaid insurance 3,247 2,067 Prepaid software subscriptions 434 146 Income tax receivable 232 — Interest receivable 461 504 Other receivable due from AstraZeneca 932 — Canadian harmonized sales tax receivable 360 290 Other 311 727 $ 9,423 $ 5,340

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following (in thousands): September 30, 2021 December 31, 2020 Accrued employee compensation and benefits $ 2,787 $ 2,551 Accrued external research and development expenses 2,239 1,037 Accrued professional and consulting fees 1,108 1,023 Other 12 48 $ 6,146 $ 4,659

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Fair Value of Options Estimated on Date of Grant Using Black-Scholes Option Pricing Model	The following table presents, on a weighted-average basis, the assumptions used in the Black-Scholes option-pricing model to determine the grant-date fair value of stock options granted: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Risk-free interest rate 1.02 % 0.33 % 0.85 % 0.70 % Expected term (in years) 6.1 6.0 6.1 6.0 Expected volatility 66.9 % 67.0 % 66.9 % 65.5 % Expected dividend yield 0 % 0 % 0 % 0 %
Summary of Stock Option Activity	The following table summarizes the Company’s stock option activity since December 31, 2020: Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value (in years) (in thousands) Outstanding as of December 31, 2020 5,607,244 $ 6.45 8.2 $ 36,628 Granted 2,750,600 10.29 Exercised (411,467 ) 1.19 Forfeited/cancelled (297,089 ) 11.36 Outstanding as of September 30, 2021 7,649,288 $ 7.92 8.3 $ 18,916 Vested and expected to vest as of September 30, 2021 7,512,688 $ 7.85 8.3 $ 18,916 Options exercisable as of September 30, 2021 2,814,127 $ 4.37 7.1 $ 13,773
Summary of Stock Based Compensation Expense	Share-based compensation expense was classified in the condensed consolidated statements of operations and comprehensive loss as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development expenses $ 728 $ 288 $ 1,913 $ 506 General and administrative expenses 1,646 953 4,324 1,519 $ 2,374 $ 1,241 $ 6,237 $ 2,025

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Basic and Diluted Net Loss per Share	Basic and diluted net loss per share attributable to common shareholders was calculated as follows (in thousands, except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Numerator: Net loss $ (19,429 ) $ (9,993 ) $ (63,811 ) $ (64,948 ) Dividends paid to preferred shareholders in the form of warrants issued — — — (1,382 ) Net loss attributable to common shareholders $ (19,429 ) $ (9,993 ) $ (63,811 ) $ (66,330 ) Denominator: Weighted-average common shares outstanding—basic and diluted 43,022,762 41,682,797 42,441,091 15,422,375 Net loss per share attributable to common shareholders —basic and diluted $ (0.45 ) $ (0.24 ) $ (1.50 ) $ (4.30 )
Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss per Share	The Company’s potentially dilutive securities, which include stock options, convertible preferred shares, preferred exchangeable shares and common share warrants, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common shareholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common shareholders for the periods indicated because including them would have had an anti-dilutive effect: Nine Months Ended September 30, 2021 2020 Options to purchase common shares 7,649,288 5,266,466 Convertible preferred shares (as converted to common shares) — — Preferred exchangeable shares (as converted to convertible preferred shares and then to common shares) — — Warrants to purchase common shares 651,816 651,816 8,301,104 5,918,282

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Component of Operating Lease Cost	The components of operating lease cost, which are included within operating expenses in the accompanying condensed consolidated statements of operations and comprehensive loss, are as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2021 Operating lease cost $ 365 $ 1,032 Variable lease cost 4 20 Total lease cost $ 369 $ 1,052
Summary of Supplemental Information of Operating Lease	The following table summarizes supplemental information for the Company’s operating leases: As of September 30, 2021 Weighted-average remaining lease term (in years) 5.5 Weighted average discount rate 4.9 % Cash paid for amounts included in the measurement of lease liabilities $ 858
Summary of Future Maturities of Operating Lease Liabilities	As of September 30, 2021, the future maturities of operating lease liabilities are as follows (in thousands): Year Ending December 31, 2021 (three months) $ 292 2022 1,427 2023 1,463 2024 1,499 2025 1,537 Thereafter 1,894 Total lease payments $ 8,112 Less: imputed interest (1,002 ) Total lease liabilities $ 7,110
Schedule of Future Minimum Rental Payments for Operating Leases	Future minimum lease payments due under operating leases as of December 31, 2020 were as follows (in thousands): Year Ending December 31, 2021 $ 1,127 2022 1,158 2023 1,190 2024 1,221 2025 1,253 Thereafter 361 Total $ 6,310

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Schedule of Recognized Expenses in Connection with Services Performed Under Master Services Agreement and Supply Agreement	The Company recognized expenses in connection with the services performed in the normal course of business under the Master Services Agreement and the Supply Agreement in the condensed consolidated statements of operations and comprehensive loss as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development expenses $ 570 $ 141 $ 1,226 $ 780 General and administrative expenses 10 23 42 50 $ 580 $ 164 $ 1,268 $ 830

Geographical Information (Table

Geographical Information (Tables)	9 Months Ended
	Sep. 30, 2021
Geographic Areas Long Lived Assets [Abstract]
Schedule of Long-lived Assets by Geographic Areas	Information about the Company’s long-lived assets, consisting solely of property and equipment, net, by geographic region was as follows (in thousands): September 30, 2021 December 31, 2020 United States $ 83 $ 103 Canada 2,377 1,864 $ 2,460 $ 1,967

Nature of the Business and Ba_2

Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jun. 30, 2020	Jun. 25, 2020	Jun. 19, 2020	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Jan. 31, 2020
Subsidiary Sale Of Stock [Line Items]
Formation and incorporation date										Dec. 31, 2014
Reverse share split, description			one-for-5.339
Net loss				$ 19,429	$ 26,853	$ 17,529	$ 9,993	$ 44,733	$ 10,222	$ 63,811	$ 64,948
Accumulated deficit				$ 177,014						$ 177,014		$ 113,203	$ (100)
Initial Public Offering [Member] | Common Shares [Member]
Subsidiary Sale Of Stock [Line Items]
Shares issued and sold, date		Jun. 25, 2020
Shares issued and sold	12,500,000	12,500,000
Shares issued and sold, per share	$ 17	$ 17						$ 17
Net proceeds of common shares	$ 193,100	$ 193,100

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	Jun. 02, 2020	Jun. 02, 2020	Jan. 31, 2020	Mar. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Oct. 31, 2019
Summary Of Significant Accounting Policies [Line Items]
Foreign currency transaction gains (losses)							$ 100,000
Restricted cash, current					$ 669,000		669,000		$ 425,000
Letters of credit										$ 1,500,000
Restricted cash, noncurrent					1,222,000		1,222,000		1,466,000
Cash, cash equivalents and restricted cash					40,300,000		40,300,000		92,400,000
Cash and cash equivalents					38,400,000		38,400,000		90,500,000
Restricted Cash					1,900,000		1,900,000		1,900,000
Deferred offering costs					300,000		300,000		$ 0
Change in fair value of preferred share tranche right liability								$ (32,722,000)
Preferred Class B [Member]
Summary Of Significant Accounting Policies [Line Items]
Preferred stock shares issued	36,806,039	36,806,039
Preferred stock price per share	$ 1.5154	$ 1.5154	$ 1.5154	$ 1.5154
Aggregate gross proceeds		$ 55,800,000	$ 10,000,000	$ 45,800,000
Change in fair value of preferred share tranche right liability							32,700,000	32,700,000
Preferred share tranche right liability			$ 1,100,000		39,600,000		39,600,000
Class B Special Voting Shares [Member]
Summary Of Significant Accounting Policies [Line Items]
Preferred stock shares issued	4,437,189	4,437,189
Preferred stock price per share	$ 0.000001	$ 0.000001
Class B Preferred Exchangable Shares [Member] | Ireland Subsidiary [Member]
Summary Of Significant Accounting Policies [Line Items]
Preferred stock shares issued	4,437,189	4,437,189
Preferred stock price per share	$ 1.5154	$ 1.5154
Aggregate gross proceeds	$ 62,500,000
Class B Convertible Preferred Shares [Member]
Summary Of Significant Accounting Policies [Line Items]
Preferred stock shares issued									132,207,290
Preferred share tranche right liability					$ 35,300,000		$ 35,300,000
Class B Convertible Preferred Shares [Member] | Ireland Subsidiary [Member]
Summary Of Significant Accounting Policies [Line Items]
Preferred stock shares issued	4,437,189	4,437,189		4,437,189	28,874,378		28,874,378
Preferred stock price per share	$ 0.000001	$ 0.000001		$ 1.5154	$ 0.001		$ 0.001
Increase in noncontrolling interest							$ 4,300,000		$ 4,300,000
AstraZeneca UK Limited [Member] | Strategic Collaboration Agreement [Member]
Summary Of Significant Accounting Policies [Line Items]
Revenue under collaboration agreement					$ 300,000		800,000
Collateralized Securities [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash, current					300,000		300,000
Restricted cash, noncurrent					1,200,000		1,200,000
Collateralize Credit Cards [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash, current					300,000		300,000		300,000
Guaranteed Investment Certificate [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash, current					100,000		$ 100,000		$ 100,000
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Foreign currency transaction gains (losses)					$ (100,000)	$ (100,000)		$ (100,000)

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Cumulative Effect of Adoption of ASC 842 on Company's Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Mar. 16, 2021	Jan. 01, 2021	Dec. 31, 2020
Summary Of Significant Accounting Policies [Line Items]
Prepaid expenses and other current assets	$ 9,423			$ 5,340
Operating lease right-of-use assets	6,946	$ 900
Total assets	268,303			310,676
Operating lease liabilities	1,327
Deferred rent, net of current portion				11
Operating lease liabilities, net of current portion	5,783
Total liabilities	$ 21,808			16,163
Impact of Adoption [Member]
Summary Of Significant Accounting Policies [Line Items]
Prepaid expenses and other current assets				(26)
Operating lease right-of-use assets				5,664
Total assets				5,638
Operating lease liabilities				959
Deferred rent, net of current portion				(11)
Operating lease liabilities, net of current portion				4,690
Total liabilities				$ 5,638
Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Summary Of Significant Accounting Policies [Line Items]
Prepaid expenses and other current assets			$ 5,314
Operating lease right-of-use assets			5,664
Total assets			316,314
Operating lease liabilities			959
Operating lease liabilities, net of current portion			4,690
Total liabilities			$ 21,801

Collaboration Agreement - Addit

Collaboration Agreement - Additional Information (Detail)	Oct. 30, 2020USD ($)collaboration	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense		$ 12,684,000	$ 4,529,000	$ 44,546,000	$ 12,231,000
Prepaid expenses and other current assets		9,423,000		9,423,000		$ 5,340,000
Deferred revenue		2,287,000		2,287,000		1,000,000
Deferred revenue, non-current		2,167,000		2,167,000		$ 4,000,000
AstraZeneca UK Limited [Member] | Strategic Collaboration Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Maximum amount for milestones payments to other party	$ 145,000,000
Research and development expense		1,600,000		2,000,000
Research and development expense offset		800,000		1,000,000
Prepaid expenses and other current assets		900,000		900,000
Upfront payment received				5,000,000
Maximum amount of payments to be received for development milestones				40,000,000
Deferred revenue		2,300,000		2,300,000
Deferred revenue, non-current		$ 2,200,000		$ 2,200,000
AstraZeneca UK Limited [Member] | Strategic Collaboration Agreement [Member] | Novel TATs And Combination Therapies [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of collaborative areas | collaboration	2

Collaboration Agreement - Sched

Collaboration Agreement - Schedule of Changes in the Contract Assets and Liabilities (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Contract assets:
Additions	$ 300
Ending balance	300
Contract liabilities:
Beginning balance	5,000
Deductions	(546)
Ending balance	$ 4,454

Collaboration Agreement - Sch_2

Collaboration Agreement - Schedule of Revenue Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Contract With Customer Asset And Liability [Abstract]
Amounts included in deferred revenue at the beginning of the period	$ 146	$ 546

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Investments
Investments	$ 222,781	$ 232,538
Corporate Bond Securities [Member]
Cash equivalents
Cash equivalents		950
Investments
Investments	28,365	26,857
Municipal Bonds [Member]
Investments
Investments	17,021	1,090
Money Market Funds [Member]
Cash equivalents
Cash equivalents	12,040	19,277
U.S Government agencies [Member]
Cash equivalents
Cash equivalents	10,949
Investments
Investments	123,936	137,089
Commercial Paper [Member]
Cash equivalents
Cash equivalents		1,000
Investments
Investments	24,788	34,471
Canadian Government Agencies [Member]
Cash equivalents
Cash equivalents		2,347
Investments
Investments	5,682	9,457
Level 1
Investments
Investments	12,040	19,277
Level 1 | Money Market Funds [Member]
Cash equivalents
Cash equivalents	12,040	19,277
Level 2
Investments
Investments	210,741	213,261
Level 2 | Corporate Bond Securities [Member]
Cash equivalents
Cash equivalents		950
Investments
Investments	28,365	26,857
Level 2 | Municipal Bonds [Member]
Investments
Investments	17,021	1,090
Level 2 | U.S Government agencies [Member]
Cash equivalents
Cash equivalents	10,949
Investments
Investments	123,936	137,089
Level 2 | Commercial Paper [Member]
Cash equivalents
Cash equivalents		1,000
Investments
Investments	24,788	34,471
Level 2 | Canadian Government Agencies [Member]
Cash equivalents
Cash equivalents		2,347
Investments
Investments	$ 5,682	$ 9,457

Investments - Schedule of Inves

Investments - Schedule of Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Available-for-sale securities, debt maturities, amortized cost [Abstract]
Amortized Cost, Due within one year or less	$ 154,155	$ 131,857
Amortized Cost, Due after one year through three years	45,574	77,063
Amortized Cost, Investments	199,729	208,920
Available-for-sale securities, debt maturities, Fair Value [Abstract]
Fair Value, Due within one year or less	154,238	131,882
Fair Value, Due after one year through three years	45,554	77,082
Fair value, Investments	$ 199,792	$ 208,964

Investments - Amortized Cost an

Investments - Amortized Cost and Estimated Fair Value of Investments by Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Investments, Amortized Cost	$ 199,729	$ 208,920
Available-for-sale Investments, Gross Unrealized Gains	101	83
Available-for-sale Investments, Gross Unrealized Losses	(38)	(39)
Available-for-sale Investments, Fair Value	199,792	208,964
Available-for-sale Investments, Current	154,238	131,882
Available-for-sale Investments, Non Current	45,554	77,082
Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Investments, Amortized Cost	24,787	34,474
Available-for-sale Investments, Gross Unrealized Gains	1	1
Available-for-sale Investments, Gross Unrealized Losses		(4)
Available-for-sale Investments, Fair Value	24,788	34,471
Available-for-sale Investments, Current	24,788	34,471
Corporate Bond Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Investments, Amortized Cost	28,327	26,855
Available-for-sale Investments, Gross Unrealized Gains	43	22
Available-for-sale Investments, Gross Unrealized Losses	(5)	(20)
Available-for-sale Investments, Fair Value	28,365	26,857
Available-for-sale Investments, Current	23,856	9,446
Available-for-sale Investments, Non Current	4,509	17,411
Municipal Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Investments, Amortized Cost	17,023	1,090
Available-for-sale Investments, Gross Unrealized Gains	2
Available-for-sale Investments, Gross Unrealized Losses	(4)
Available-for-sale Investments, Fair Value	17,021	1,090
Available-for-sale Investments, Current	14,766	1,090
Available-for-sale Investments, Non Current	2,255
Canadian Government Agencies Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Investments, Amortized Cost	5,637	9,405
Available-for-sale Investments, Gross Unrealized Gains	45	52
Available-for-sale Investments, Fair Value	5,682	9,457
Available-for-sale Investments, Current	4,578	6,154
Available-for-sale Investments, Non Current	1,104	3,303
U.S. Government Agencies [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Investments, Amortized Cost	123,955	137,096
Available-for-sale Investments, Gross Unrealized Gains	10	8
Available-for-sale Investments, Gross Unrealized Losses	(29)	(15)
Available-for-sale Investments, Fair Value	123,936	137,089
Available-for-sale Investments, Current	86,250	80,721
Available-for-sale Investments, Non Current	$ 37,686	$ 56,368

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Prepaid Expense And Other Assets Current [Abstract]
Prepaid external research and development expenses	$ 3,446	$ 1,606
Prepaid insurance	3,247	2,067
Prepaid software subscriptions	434	146
Income tax receivable	232
Interest receivable	461	504
Other receivable due from AstraZeneca	932
Canadian harmonized sales tax receivable	360	290
Other	311	727
Prepaid expenses and other current assets	$ 9,423	$ 5,340

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued employee compensation and benefits	$ 2,787	$ 2,551
Accrued external research and development expenses	2,239	1,037
Accrued professional and consulting fees	1,108	1,023
Other	12	48
Accrued expenses	$ 6,146	$ 4,659

Equity - Additional Information

Equity - Additional Information (Detail)	Jul. 02, 2021USD ($)	Jun. 30, 2020USD ($)$ / sharesshares	Jun. 25, 2020USD ($)$ / sharesshares	Jun. 19, 2020	Jun. 02, 2020USD ($)$ / sharesshares	Jun. 02, 2020USD ($)$ / sharesshares	Jan. 31, 2020USD ($)$ / sharesshares	Mar. 31, 2019USD ($)$ / sharesshares	Jun. 30, 2020USD ($)$ / shares	Mar. 31, 2020USD ($)	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)$ / sharesshares	Oct. 17, 2020shares
Class Of Stock [Line Items]
Reverse share split, description				one-for-5.339
Stockholders equity note stock split conversion ratio				0.187
Common stock, no par value | $ / shares
Common stock, voting rights description											Each common share entitles the holder to one vote on all matters submitted to a vote of the Company’s shareholders.
Cash dividends											$ 0
Issuance of preferred shares and tranche right, issuance costs											216,000	$ 4,572,000
Number of shares issuable upon exercise of outstanding warrants (in shares) | shares							749,197
Weighted-average exercise price per share (in dollars per share) | $ / shares							$ 8.10
Expiration period							2 years
Preferred share warrant liability							$ 1,400,000
Decrease in additional Paid in Capital							1,300,000
Accumulated deficit							$ 100,000				$ (177,014,000)		$ (113,203,000)
Common stock, shares issued | shares											43,066,219		41,725,797
Class B Convertible Preferred Shares [Member]
Class Of Stock [Line Items]
Stockholders equity note stock split conversion ratio											0.05339
Preferred stock shares issued | shares													132,207,290
Preferred share tranche right liability											$ 35,300,000
Preferred shares tranche liability													$ 35,300,000
Class B Convertible Preferred Shares [Member] | Ireland Subsidiary [Member]
Class Of Stock [Line Items]
Preferred stock shares issued | shares					4,437,189	4,437,189		4,437,189			28,874,378
Preferred stock price per share | $ / shares					$ 0.000001	$ 0.000001		$ 1.5154			$ 0.001
Increase in noncontrolling interest											$ 4,300,000		$ 4,300,000
Preferred Class A
Class Of Stock [Line Items]
Preferred stock, no par value | $ / shares
Preferred Class B [Member]
Class Of Stock [Line Items]
Preferred stock shares issued | shares					36,806,039	36,806,039
Preferred stock, no par value | $ / shares
Sold and issued of common stock | shares						36,806,039	6,598,917	30,207,129
Preferred stock price per share | $ / shares					$ 1.5154	$ 1.5154	$ 1.5154	$ 1.5154
Aggregate gross proceeds						$ 55,800,000	$ 10,000,000	$ 45,800,000
Purchase an aggregate preferred share							20,000
Issuance of preferred shares and tranche right, issuance costs							100,000
Preferred share tranche right liability							$ 1,100,000				39,600,000
Loss on tranche liability contract											$ 32,700,000		$ 32,700,000
Preferred shares tranche liability													$ 39,600,000
Preferred Class B [Member] | Canada Pension Plan Investment Board
Class Of Stock [Line Items]
Sold and issued of common stock | shares											6,598,917
Preferred stock price per share | $ / shares											$ 1.5154
Class B Convertible Preferred Shares and Class B Preferred Share Tranche Right [Member]
Class Of Stock [Line Items]
Issuance of preferred shares and tranche right, issuance costs									$ 6,000	$ 93,000
Number of shares issuable upon exercise of outstanding warrants (in shares) | shares							3,126,391
Weighted-average exercise price per share (in dollars per share) | $ / shares							$ 1.5154
Class B Preferred Exchangable Shares [Member]
Class Of Stock [Line Items]
Number of shares issuable upon exercise of outstanding warrants (in shares) | shares							873,609
Weighted-average exercise price per share (in dollars per share) | $ / shares							$ 1.5154
Class B Preferred Exchangable Shares [Member] | Ireland Subsidiary [Member]
Class Of Stock [Line Items]
Preferred stock shares issued | shares					4,437,189	4,437,189
Preferred stock price per share | $ / shares					$ 1.5154	$ 1.5154
Aggregate gross proceeds					$ 62,500,000
Open Market Sales Agreement [Member]
Class Of Stock [Line Items]
Net proceeds of common shares											$ 0
Open Market Sales Agreement [Member] | Maximum [Member]
Class Of Stock [Line Items]
Net proceeds of common shares	$ 100,000,000
Compensation percentage of gross proceeds	3.00%
Class B Special Voting Shares [Member]
Class Of Stock [Line Items]
Preferred stock price per share | $ / shares							$ 0.000001
Class B Special Voting Shares [Member] | Class B Convertible Preferred Shares [Member]
Class Of Stock [Line Items]
Stockholders equity note stock split conversion ratio						0.05339
Preferred stock shares issued | shares					4,437,189	4,437,189		4,437,189			28,874,378
Preferred stock price per share | $ / shares					$ 1.5154	$ 1.5154		$ 0.000001			$ 0.000001
Aggregate gross proceeds						$ 6,700,000		$ 6,700,000
Warrant Liability [Member]
Class Of Stock [Line Items]
Loss related to increase in fair value of the Preferred Share Warrants											$ 6,400,000
Common share warrants, exercised | shares														97,381
Common stock, shares issued | shares														38,340
Number of warrants cancelled | shares														59,041
Common share warrants remained outstanding | shares														651,816
Initial Public Offering [Member] | Common Shares [Member]
Class Of Stock [Line Items]
Shares issued and sold, date			Jun. 25, 2020
Shares issued and sold | shares		12,500,000	12,500,000
Shares issued and sold, per share | $ / shares		$ 17	$ 17						$ 17
Net proceeds of common shares		$ 193,100,000	$ 193,100,000

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares option, exercised	$ 3.3
Weighted average grant-date fair value of stock options granted	$ 6.17	$ 11.54
Aggregate unrecognized share-based compensation expense	$ 25.4
Unrecognized share-based compensation expense, weighted average period expects for recognition	2 years 9 months 18 days
2020 Stock Option and incentive plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock reserved for future issuance	4,273,350	6,151,833
Stock incentive plan description	cumulatively increased each January 1 thereafter by 4% of the number of the Company’s common shares outstanding on the immediately preceding December 31 or such lesser number of shares determined by the Company’s compensation committee of the board of directors
Annual percentage increase in common stock reserved for future issuance	4.00%
Number of shares remained available for future grant	2,575,208
2017 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock reserved for future issuance	0		0
Number of shares remained available for future grant	0		0
2020 Employee Share Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock reserved for future issuance	450,169
Stock incentive plan description	the number of common shares that may be issued under the ESPP was automatically increased on January 1, 2021 and shall be automatically increased each January 1 thereafter by the lesser of (i) 900,338 common shares, (ii) 1% of the number of the Company’s common shares outstanding on the immediately preceding December 31 and (iii) such lesser number of shares as determined by the Company’s compensation committee of the board of directors.
Annual percentage increase in common stock reserved for future issuance	1.00%
Maximum annual increase in common stock reserved for future issuance	900,338
Shares, Issued	15,596

Share-Based Compensation - Fair

Share-Based Compensation - Fair Value of Options Estimated on Date of Grant Using Black-Scholes Option Pricing Model (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	1.02%	0.33%	0.85%	0.70%
Expected term (in years)	6 years 1 month 6 days	6 years	6 years 1 month 6 days	6 years
Expected volatility	66.90%	67.00%	66.90%	65.50%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Beginning balance | shares	5,607,244
Number of Shares, Granted | shares	2,750,600
Number of Shares, Exercised | shares	(411,467)
Number of Shares, Forfeited/cancelled | shares	(297,089)
Number of Shares, Ending balance | shares	7,649,288	5,607,244
Number of Shares, Options vested and expected to vest | shares	7,512,688
Number of Shares, Options exercisable | shares	2,814,127
Weighted Average Exercise Price, Beginning balance | $ / shares	$ 6.45
Weighted Average Exercise Price, Granted | $ / shares	10.29
Weighted Average Exercise Price, Exercised | $ / shares	1.19
Weighted Average Exercise Price, Forfeited/cancelled | $ / shares	11.36
Weighted Average Exercise Price, Ending balance | $ / shares	7.92	$ 6.45
Weighted Average Exercise Price, Options vested and expected to vest | $ / shares	7.85
Weighted Average Exercise Price, Options exercisable | $ / shares	$ 4.37
Weighted-Average Remaining Contractual Term, Outstanding	8 years 3 months 18 days	8 years 2 months 12 days
Weighted Average Remaining Contractual Term, Options vested and expected to vest	8 years 3 months 18 days
Weighted Average Remaining Contractual Term, Options exercisable	7 years 1 month 6 days
Aggregate Intrinsic Value | $	$ 18,916	$ 36,628
Aggregate Intrinsic Value, Options vested and expected to vest | $	18,916
Aggregate Intrinsic Value, Options exercisable | $	$ 13,773

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 2,374	$ 1,241	$ 6,237	$ 2,025
Research and Development Expense [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	728	288	1,913	506
General and Administrative Expense [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 1,646	$ 953	$ 4,324	$ 1,519

License Agreements and Asset _2

License Agreements and Asset Acquisitions - Additional Information (Detail) € in Millions	Aug. 12, 2021CAD ($)	Mar. 01, 2021USD ($)	Mar. 01, 2021EUR (€)shares	Sep. 30, 2021USD ($)shares	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)shares	Sep. 30, 2020USD ($)	Sep. 30, 2021CAD ($)shares	Dec. 31, 2020shares
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research and development				$ 12,684,000	$ 4,529,000	$ 44,546,000	$ 12,231,000
Common stock, shares issued | shares				43,066,219		43,066,219		43,066,219	41,725,797
CPDC [Member] | Research and License Agreement [Member] | Research and Development Expense [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payment				$ 0	0	$ 0	0
ImmunoGen [Member] | Research and License Agreement [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront license fee paid						200,000
Research and development				0	0	0	0
ImmunoGen [Member] | Research and License Agreement [Member] | Maximum [Member] | Development And Regulatory Milestone [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Performance milestone payments based on successful development				15,000,000		15,000,000
ImmunoGen [Member] | Research and License Agreement [Member] | Maximum [Member] | Sales Based Milestone [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Performance milestone payments based on successful development				35,000,000		35,000,000
ImmunoGen [Member] | Research and License Agreement [Member] | Research and Development Expense [Member] | Development And Regulatory Milestone [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront license fee paid				0	0	0	0
MediaPharma [Member] | Asset Acquisition and License Agreement [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront license fee paid						200,000
Research and development				0	0	0	0
MediaPharma [Member] | Asset Acquisition and License Agreement [Member] | Maximum [Member] | Development And Regulatory Milestone [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Performance milestone payments based on successful development				1,500,000		1,500,000
MediaPharma [Member] | Asset Acquisition and License Agreement [Member] | Maximum [Member] | Sales Based Milestone [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Performance milestone payments based on successful development				23,000,000		23,000,000
Rainier Therapeutics, Inc. [Member] | Research and Development Expense [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront license fee paid							1,000,000
Research and development				0
Rainier Therapeutics, Inc. [Member] | Asset Acquisition and License Agreement [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payment						2,000,000
Additional amount payable under agreement				$ 3,500,000		$ 3,500,000
Non-voting common stock, issued | shares				313,359		313,359		313,359
Rainier Therapeutics, Inc. [Member] | Asset Acquisition and License Agreement [Member] | Development And Regulatory Milestone [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Performance milestone payments based on successful development				$ 22,500,000		$ 22,500,000
Non-voting common stock, issued | shares				156,679		156,679		156,679
Rainier Therapeutics, Inc. [Member] | Asset Acquisition and License Agreement [Member] | Sales Based Milestone [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Performance milestone payments based on successful development				$ 42,000,000		$ 42,000,000
Rainier Therapeutics, Inc. [Member] | Asset Acquisition and License Agreement [Member] | Phase1
Research And Development Arrangement Contract To Perform For Others [Line Items]
Non-voting common stock, issued | shares				156,679		156,679		156,679
Rainier Therapeutics, Inc. [Member] | Asset Acquisition and License Agreement [Member] | Maximum [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential future payment as percentage of amount the Company receives under sublicense agreements				30.00%		30.00%		30.00%
Rainier Therapeutics, Inc. [Member] | Asset Acquisition and License Agreement [Member] | Minimum [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Potential future payment as percentage of amount the Company receives under sublicense agreements				10.00%		10.00%		10.00%
Rainier Therapeutics, Inc. [Member] | Asset Acquisition and License Agreement [Member] | Research and Development Expense [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront license fee paid						$ 1,000,000
Research and development						6,100,000
Additional amount payable under agreement				$ 3,500,000		$ 3,500,000
Non-voting common stock, issued | shares				313,359		313,359		313,359
Payment of research and development expenses						$ 3,500,000
Genentech, Inc. [Member] | Asset Acquisition and License Agreement [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research and development				$ 0	0	0	0
Genentech, Inc. [Member] | Asset Acquisition and License Agreement [Member] | Maximum [Member] | Sales Based Milestone [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Performance milestone payments based on successful development				44,000,000		44,000,000
Yumab GmbH [Member] | Asset Acquisition and License Agreement [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research and development				0	$ 200,000	0	$ 200,000
Yumab GmbH [Member] | Asset Acquisition and License Agreement [Member] | Development And Regulatory Milestone [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Performance milestone payments based on successful development				3,900,000		3,900,000
TRIUMF Innovations Inc. [Member] | Asset Acquisition and License Agreement [Member] | Accounts Payable [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Total milestone payment achieved				2,300,000		2,300,000		$ 3,000,000
TRIUMF Innovations Inc. [Member] | Asset Acquisition and License Agreement [Member] | Development And Regulatory Milestone [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Performance milestone payments based on successful development								5,000,000
TRIUMF Innovations Inc. [Member] | Asset Acquisition and License Agreement [Member] | Maximum [Member] | Actinium-225 [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Additional financial investment	$ 15,000,000
TRIUMF Innovations Inc. [Member] | Asset Acquisition and License Agreement [Member] | Minimum [Member] | Actinium-225 [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Percentage of annual requirements	50.00%
TRIUMF Innovations Inc. [Member] | Asset Acquisition and License Agreement [Member] | Research and Development Expense [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Amortization expenses				500,000		1,400,000
TRIUMF Innovations Inc. [Member] | Collaboration Agreement and Amended Collaboration Agreement [Member] | Prepaid Expenses and Other Current Assets [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payment						2,200,000
TRIUMF Innovations Inc. [Member] | Collaboration Agreement and Amended Collaboration Agreement [Member] | Other Non-current Assets [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payment						2,700
TRIUMF Innovations Inc. [Member] | Amended Collaboration Agreement [Member] | Accounts Payable [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Total milestone payment achieved				3,900,000		3,900,000		$ 5,000,000
TRIUMF Innovations Inc. [Member] | Amended Collaboration Agreement [Member] | Research and Development Expense [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Amortization expenses				0		0
Ipsen Pharma S A S | Asset Acquisition and License Agreement [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront license fee paid		$ 800,000	€ 0.6
Research and development				$ 0		$ 6,400,000
Non-voting common stock, issued | shares				600,000,000,000		600,000,000,000		600,000,000,000
Common stock, shares issued | shares			600,000
Additional amount to be paid upon achievment of development and regulatory milestone | €			€ 67.5
Additional amount to be paid on net sales | €			350
Third party licensor fees payable | €			€ 70
Acquisition of inventory						$ 800,000
Ipsen Pharma S A S | Asset Acquisition and License Agreement [Member] | Maximum [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Decrease in percentage of royalties						50.00%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Income tax (provision) benefit	$ 48	$ (185)	$ 55	$ 27
Irish Subsidiary [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets	0		$ 0		$ 0
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Income tax (provision) benefit	$ 100			$ 100

Net Loss per Share - Basic and

Net Loss per Share - Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss	$ (19,429)	$ (26,853)	$ (17,529)	$ (9,993)	$ (44,733)	$ (10,222)	$ (63,811)	$ (64,948)
Dividends paid to preferred shareholders in the form of warrants issued								(1,382)
Net loss attributable to common shareholders	$ (19,429)			$ (9,993)			$ (63,811)	$ (66,330)
Denominator:
Weighted-average common shares outstanding—basic and diluted	43,022,762			41,682,797			42,441,091	15,422,375
Net loss per share attributable to common shareholders—basic and diluted	$ (0.45)			$ (0.24)			$ (1.50)	$ (4.30)

Net Loss per Share - Summary of

Net Loss per Share - Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss per Share (Detail) - shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share	8,301,104	5,918,282
Options to purchase common shares [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share	7,649,288	5,266,466
Warrant Liability [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share	651,816	651,816

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Thousands	Jun. 01, 2021	Mar. 16, 2021	Jul. 31, 2020	Oct. 31, 2019	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Lessee Lease Description [Line Items]
Non-cancelable minimum purchase commitments			$ 100			$ 400
Lease expiration date			Jul. 31, 2023
Operating lease expiration period	Sep. 30, 2037			Feb. 28, 2026		Aug. 31, 2030
Operating lease additional lease period	5 years					5 years
Operating lease termination notice period						12 months
Operating lease, option to extend by lessee						false
Lessee, operating lease, description						In August 2018, the Company entered into an operating lease for office space in Hamilton, Ontario. This lease was amended in September 2020 (“New Lease Commencement Date”) and expires in August 2030 with a termination option upon twelve months written notice any time after the fifth anniversary of the New Lease Commencement Date.  If the termination option is not exercised, the Company may exercise a renewal option to extend the term for an additional five-year period to August 2035. As the Company is not reasonably certain to extend the lease beyond the allowable termination date, the lease term was determined to end in August 2026 for the purposes of measuring this lease.
Restricted cash						$ 1,900		$ 1,900
Restricted cash, current						669		425
Restricted cash, noncurrent						$ 1,222		1,466
Allowance for lease improvements		$ 200
Lease improvements and expansions, description						The Company currently expects the rent for the Expansion Space, which is under construction, to commence on January 1, 2022.
Lease, option to extend	The Company currently expects the rent for the manufacturing facility, which is under construction, to commence in October 2022, approximately two months after the anticipated delivery date of the premises.  The Company currently expects the lease end date for the manufacturing facility to be in September 2037, with a five-year renewal option.					The Company currently expects the lease end date for the Original Premises and the Expansion Premises lease to be April 30, 2027, with no option to extend the lease term.
Operating lease right-of-use assets		900				$ 6,946
Increase in operating lease liability		$ 1,200				7,110
Lease and rental expense					$ 300		$ 800
Other Non-current Assets [Member]
Lessee Lease Description [Line Items]
Prepaid rent						2,100
Canada, Dollars
Lessee Lease Description [Line Items]
Sales-type lease, initial direct cost expense	$ 2,500
United States of America, Dollars
Lessee Lease Description [Line Items]
Sales-type lease, initial direct cost expense	$ 2,100
Letter of Credit [Member]
Lessee Lease Description [Line Items]
Restricted cash						1,500
Restricted cash, current						300
Restricted cash, noncurrent						$ 1,200

Leases - Component of Operating

Leases - Component of Operating Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Lease Cost [Abstract]
Operating lease cost	$ 365	$ 1,032
Variable lease cost	4	20
Total lease cost	$ 369	$ 1,052

Leases - Summary of Supplementa

Leases - Summary of Supplemental Information, Operating Lease (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Leases [Abstract]
Weighted-average remaining lease term (in years)	5 years 6 months
Weighted average discount rate	4.90%
Cash paid for amounts included in the measurement of lease liabilities	$ 858

Leases - Summary of Future Matu

Leases - Summary of Future Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Mar. 16, 2021
Operating Lease Liabilities Payments Due [Abstract]
2021 (three months)	$ 292
2022	1,427
2023	1,463
2024	1,499
2025	1,537
Thereafter	1,894
Total lease payments	8,112
Less: imputed interest	(1,002)
Total lease liabilities	$ 7,110	$ 1,200

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Rental Payments for Operating Lease (Details) $ in Thousands	Sep. 30, 2021USD ($)
Leases [Abstract]
2021	$ 1,127
2022	1,158
2023	1,190
2024	1,221
2025	1,253
Thereafter	361
Total	$ 6,310

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Jul. 31, 2020	Sep. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Non-cancelable minimum purchase commitments	$ 0.1	$ 0.4
C P D C
Defined Benefit Plan Disclosure [Line Items]
Non-cancelable minimum purchase commitments		$ 0.8

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) $ in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2021CAD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Related Party Transaction [Line Items]
Research and development expense	$ 12,684	$ 4,529	$ 44,546		$ 12,231
C P D C
Related Party Transaction [Line Items]
Payment related to supply agreement per quarter	200		200
Payment related to supply agreement aggregate per year	800		800
Amounts of transaction related to service	500	200	1,400		1,000
Amount due to related parties	300		300			$ 300
Research and development expense	570	141	1,226		780
C P D C | C A- O N
Related Party Transaction [Line Items]
Research and development expense			3,000	$ 2.5
C P D C | Maximum [Member]
Related Party Transaction [Line Items]
Payment for reimbursement of pass through costs	$ 100	$ 100	$ 200		$ 100

Related Party Transactions - Sc

Related Party Transactions - Schedule of Recognized Expenses in Connection with Services Performed Under Master Services Agreement and Supply Agreement (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Related Party Transaction [Line Items]
Research and development expense	$ 12,684	$ 4,529	$ 44,546	$ 12,231
General and administrative expenses	7,156	5,790	20,762	14,105
C P D C
Related Party Transaction [Line Items]
Research and development expense	570	141	1,226	780
General and administrative expenses	10	23	42	50
Total operating expenses	$ 580	$ 164	$ 1,268	$ 830

Geographical Information - Sche

Geographical Information - Schedule of Long-lived Assets by Geographic Areas (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	$ 2,460	$ 1,967
United States [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	83	103
Canada [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net	$ 2,377	$ 1,864