Arbutus Biopharma (ABUS) 10-Q 5 Nov 20 2020 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2020	Nov. 05, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-34949
Entity Registrant Name	ARBUTUS BIOPHARMA CORP
Amendment Flag	false
Entity Central Index Key	0001447028
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Incorporation, State or Country Code	A1
Entity Tax Identification Number	98-0597776
Entity Address, Address Line One	701 Veterans Circle
Entity Address, City or Town	Warminster
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	18974
City Area Code	267
Local Phone Number	469-0914
Title of 12(b) Security	Common Shares, without par value
Trading Symbol	ABUS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		84,909,258

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 96,918	$ 31,799
Investments in marketable securities, current	21,378	59,035
Accounts receivable	1,075	1,204
Prepaid expenses and other current assets	1,871	1,790
Total current assets	121,242	93,828
Property and equipment, net of accumulated depreciation of $7,133 (December 31, 2019: $5,642)	7,262	8,676
Right of use asset	2,491	2,738
Other non-current assets	109	293
Total assets	131,104	105,535
Current liabilities:
Accounts payable and accrued liabilities	6,913	7,235
Liability-classified options	317	253
Lease liability, current	378	340
Total current liabilities	7,608	7,828
Liability related to sale of future royalties	20,117	18,992
Contingent consideration	3,301	2,953
Lease liability, non-current	2,733	3,018
Total liabilities	33,759	32,791
Stockholders’ equity:
Preferred shares, Authorized; unlimited number without par value; Issued and outstanding: 1,164,000 (December 31, 2019: 1,164,000)	146,285	137,285
Common shares, Authorized - unlimited number with no par value, Issued and outstanding: 84,618,575 (December 31, 2019 - 64,780,314)	965,369	898,535
Additional paid-in capital	59,614	55,246
Deficit	(1,025,796)	(970,093)
Accumulated other comprehensive loss	(48,127)	(48,229)
Total stockholders’ equity	97,345	72,744
Total liabilities and stockholders’ equity	$ 131,104	$ 105,535

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Accumulated of property, plant, and equipment	$ 7,133	$ 5,642
Preferred stock, shares issued (in shares)	1,164,000	1,164,000
Preferred stock, shares outstanding (in shares)	1,164,000	1,164,000
Common shares, shares issued (in shares)	84,618,575	64,780,314
Common shares, shares outstanding (in shares)	84,618,575	64,780,314

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue
Revenue	$ 1,523	$ 3,061	$ 4,528	$ 4,393
Operating expenses
Research and development	12,065	17,731	32,946	45,183
General and administrative	4,065	3,249	11,184	15,850
Depreciation and amortization	490	507	1,491	1,521
Change in fair value of contingent consideration	120	(376)	348	(121)
Site consolidation	0	182	64	33
Impairment of intangible assets	0	43,836	0	43,836
Impairment of goodwill	0	22,471	0	22,471
Arbitration	0	6,486	0	6,486
Total operating expenses	16,740	94,086	46,033	135,259
Loss from operations	(15,217)	(91,025)	(41,505)	(130,866)
Interest income	100	503	645	1,709
Interest expense	(1,074)	(1,100)	(3,214)	(1,114)
Foreign exchange gain (loss)	(19)	(25)	(84)	43
Equity investment loss	(2,545)	(3,512)	(2,545)	(11,497)
Total other loss	(3,538)	(4,134)	(5,198)	(10,859)
Loss before income taxes	(18,755)	(95,159)	(46,703)	(141,725)
Income tax benefit	0	12,656	0	12,656
Net loss	(18,755)	(82,503)	(46,703)	(129,069)
Items applicable to preferred shares:
Dividend accretion of convertible preferred shares	(3,027)	(2,792)	(9,000)	(8,269)
Net loss attributable to common shares	$ (21,782)	$ (85,295)	$ (55,703)	$ (137,338)
Loss per share
Basic and diluted (in USD per share)	$ (0.27)	$ (1.50)	$ (0.77)	$ (2.43)
Weighted average number of common shares
Basic and diluted (in shares)	79,487,444	56,850,172	72,342,070	56,469,358
Unrealized gain on available-for-sale securities	$ (72)	$ 0	$ 58	$ 0
Currency translation adjustments	44	27	44	(47)
Comprehensive loss	(18,783)	(82,476)	(46,601)	(129,116)
Collaborations and licenses
Revenue
Revenue	827	2,600	2,487	3,414
Non-cash royalty revenue
Revenue
Revenue	$ 696	$ 461	$ 2,041	$ 979

Condensed Consolidated Statem_2

Condensed Consolidated Statement of Stockholders’ Equity (Unaudited) - USD ($)	Total	Convertible Preferred Shares	Common Shares	Additional Paid-In Capital	Deficit	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2018		1,164,000	55,518,800
Beginning balance at Dec. 31, 2018	$ 200,234,000	$ 126,136,000	$ 879,405,000	$ 48,084,000	$ (805,221,000)	$ (48,170,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of accumulated dividends on Preferred Shares	0	$ 2,715,000			(2,715,000)
Stock-based compensation	1,665,000			1,665,000
Certain fair value adjustments to liability stock option awards	47,000			47,000
Issuance of common shares pursuant to the Open Market Sales Agreement (in shares)			614,401
Issuance of common shares pursuant to the Open Market Sales Agreement			$ 2,248,000
Issuance of common shares pursuant to the Open Market Sales Agreement	2,248,000
Issuance of common shares pursuant to exercise of options (in shares)			122,603
Issuance of common shares pursuant to exercise of options	288,000		$ 490,000	(202,000)
Currency translation adjustments	(22,000)					(22,000)
Net loss	(23,251,000)				(23,251,000)
Ending balance (in shares) at Mar. 31, 2019		1,164,000	56,255,804
Ending balance at Mar. 31, 2019	181,209,000	$ 128,851,000	$ 882,143,000	49,594,000	(831,187,000)	(48,192,000)
Beginning balance (in shares) at Dec. 31, 2018		1,164,000	55,518,800
Beginning balance at Dec. 31, 2018	200,234,000	$ 126,136,000	$ 879,405,000	48,084,000	(805,221,000)	(48,170,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(129,069,000)
Ending balance (in shares) at Sep. 30, 2019		1,164,000	56,850,172
Ending balance at Sep. 30, 2019	83,637,000	$ 134,405,000	$ 884,623,000	55,385,000	(942,559,000)	(48,217,000)
Beginning balance (in shares) at Mar. 31, 2019		1,164,000	56,255,804
Beginning balance at Mar. 31, 2019	181,209,000	$ 128,851,000	$ 882,143,000	49,594,000	(831,187,000)	(48,192,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of accumulated dividends on Preferred Shares	0	$ 2,762,000			(2,762,000)
Stock-based compensation	3,915,000			3,915,000
Certain fair value adjustments to liability stock option awards	230,000			230,000
Issuance of common shares pursuant to the Open Market Sales Agreement (in shares)			593,689
Issuance of common shares pursuant to the Open Market Sales Agreement			$ 2,477,000
Issuance of common shares pursuant to the Open Market Sales Agreement	2,477,000
Issuance of common shares pursuant to exercise of options (in shares)			679
Issuance of common shares pursuant to exercise of options	2,000		$ 3,000	(1,000)
Currency translation adjustments	(52,000)					(52,000)
Net loss	(23,315,000)				(23,315,000)
Ending balance (in shares) at Jun. 30, 2019		1,164,000	56,850,172
Ending balance at Jun. 30, 2019	164,466,000	$ 131,613,000	$ 884,623,000	53,738,000	(857,264,000)	(48,244,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of accumulated dividends on Preferred Shares	0	$ 2,792,000			(2,792,000)
Stock-based compensation	1,592,000			1,592,000
Certain fair value adjustments to liability stock option awards	55,000			55,000
Currency translation adjustments	27,000					27,000
Net loss	(82,503,000)				(82,503,000)
Ending balance (in shares) at Sep. 30, 2019		1,164,000	56,850,172
Ending balance at Sep. 30, 2019	83,637,000	$ 134,405,000	$ 884,623,000	55,385,000	(942,559,000)	(48,217,000)
Beginning balance (in shares) at Dec. 31, 2019		1,164,000	64,780,314
Beginning balance at Dec. 31, 2019	72,744,000	$ 137,285,000	$ 898,535,000	55,246,000	(970,093,000)	(48,229,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of accumulated dividends on Preferred Shares	0	$ 2,978,000			(2,978,000)
Stock-based compensation	1,460,000			1,460,000
Certain fair value adjustments to liability stock option awards	180,000			180,000
Issuance of common shares pursuant to the Open Market Sales Agreement (in shares)			4,147,081
Issuance of common shares pursuant to the Open Market Sales Agreement			$ 12,315,000
Issuance of common shares pursuant to the Open Market Sales Agreement	12,315,000
Issuance of common shares pursuant to exercise of options (in shares)			34,000
Issuance of common shares pursuant to exercise of options	166,000		$ 249,000	(83,000)
Unrealized gain on available-for-sale securities	252,000					252,000
Net loss	(13,861,000)				(13,861,000)
Ending balance (in shares) at Mar. 31, 2020		1,164,000	68,961,395
Ending balance at Mar. 31, 2020	73,256,000	$ 140,263,000	$ 911,099,000	56,803,000	(986,932,000)	(47,977,000)
Beginning balance (in shares) at Dec. 31, 2019		1,164,000	64,780,314
Beginning balance at Dec. 31, 2019	72,744,000	$ 137,285,000	$ 898,535,000	55,246,000	(970,093,000)	(48,229,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(46,703,000)
Ending balance (in shares) at Sep. 30, 2020		1,164,000	84,618,575
Ending balance at Sep. 30, 2020	97,345,000	$ 146,285,000	$ 965,369,000	59,614,000	(1,025,796,000)	(48,127,000)
Beginning balance (in shares) at Mar. 31, 2020		1,164,000	68,961,395
Beginning balance at Mar. 31, 2020	73,256,000	$ 140,263,000	$ 911,099,000	56,803,000	(986,932,000)	(47,977,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of accumulated dividends on Preferred Shares	0	$ 2,995,000			(2,995,000)
Stock-based compensation	1,597,000			1,597,000
Certain fair value adjustments to liability stock option awards	(92,000)			(92,000)
Issuance of common shares pursuant to the Open Market Sales Agreement (in shares)			2,291,184
Issuance of common shares pursuant to the Open Market Sales Agreement			$ 5,045,000
Issuance of common shares pursuant to the Open Market Sales Agreement	5,045,000
Issuance of common shares pursuant to exercise of options (in shares)			4,000
Issuance of common shares pursuant to exercise of options	(86,000)		$ (78,000)	(8,000)
Unrealized gain on available-for-sale securities	(122,000)					(122,000)
Net loss	(14,087,000)				(14,087,000)
Ending balance (in shares) at Jun. 30, 2020		1,164,000	71,256,579
Ending balance at Jun. 30, 2020	65,511,000	$ 143,258,000	$ 916,066,000	58,300,000	(1,004,014,000)	(48,099,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of accumulated dividends on Preferred Shares	0	$ 3,027,000			(3,027,000)
Stock-based compensation	1,658,000			1,658,000
Certain fair value adjustments to liability stock option awards	(137,000)			(137,000)
Issuance of common shares pursuant to the Open Market Sales Agreement (in shares)			13,258,096
Issuance of common shares pursuant to the Open Market Sales Agreement			$ 48,760,000
Issuance of common shares pursuant to the Open Market Sales Agreement	48,760,000
Issuance of common shares pursuant to exercise of options (in shares)			103,900
Issuance of common shares pursuant to exercise of options	336,000		$ 543,000	(207,000)
Unrealized gain on available-for-sale securities	(72,000)					(72,000)
Currency translation adjustments	44,000					44,000
Net loss	(18,755,000)				(18,755,000)
Ending balance (in shares) at Sep. 30, 2020		1,164,000	84,618,575
Ending balance at Sep. 30, 2020	$ 97,345,000	$ 146,285,000	$ 965,369,000	$ 59,614,000	$ (1,025,796,000)	$ (48,127,000)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flow (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
OPERATING ACTIVITIES
Net loss	$ (46,703)	$ (129,069)
Non-cash items:
Deferred income tax benefit	0	(12,661)
Depreciation	1,491	1,521
Gain on sale of property and equipment	0	(11)
Stock-based compensation expense	4,730	6,822
Unrealized foreign exchange losses (gains)	56	(71)
Change in fair value of contingent consideration	348	(121)
Impairment of intangible assets	0	43,836
Impairment of goodwill	0	22,471
Net equity investment loss	2,544	11,497
Non-cash royalty revenue	(2,041)	(979)
Non-cash interest expense	3,166	1,106
Net accretion and amortization of investments in marketable securities	71	0
Net change in operating items:
Accounts receivable	129	(1,057)
Prepaid expenses and other assets	350	1,839
Accounts payable and accrued liabilities	(147)	(1,320)
Restructuring accrual	(137)	(917)
Other liabilities	(285)	(541)
Net cash used in operating activities	(36,428)	(57,655)
INVESTING ACTIVITIES
Purchase of investments	(28,904)	0
Disposition of investments	66,548	87,675
Investment in Genevant	(2,500)	0
Proceeds from sale of property and equipment	0	11
Acquisition of property and equipment	(77)	(526)
Net cash provided by investing activities	35,067	87,160
FINANCING ACTIVITIES
Proceeds from sale of future royalties, net	0	18,549
Issuance of common shares pursuant to the Open Market Sale agreement	66,120	4,725
Issuance of common shares pursuant to exercise of options	416	290
Net cash provided by financing activities	66,536	23,564
Effect of foreign exchange rate changes on cash and cash equivalents	(56)	71
Increase in cash and cash equivalents	65,119	53,140
Cash and cash equivalents, beginning of period	31,799	36,942
Cash and cash equivalents, end of period	96,918	90,082
Supplemental cash flow information
Preferred shares dividends accrued	$ (9,000)	$ (5,477)

Nature of business and future o

Nature of business and future operations	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of business and future operations	Nature of business and future operations Arbutus Biopharma Corporation (the “Company” or “Arbutus”) is a clinical-stage biopharmaceutical company primarily focused on developing a cure for people with chronic hepatitis B virus (“HBV”) infection. The Company is advancing multiple drug product candidates that may be combined into a potentially curative regimen for chronic HBV infection. Arbutus has also initiated a drug discovery and development effort for treating coronaviruses, including COVID-19. The Company’s pipeline includes: • AB-729, a subcutaneously-delivered RNA interference (“RNAi”) product candidate currently in a Phase 1a/1b clinical trial. Preliminary positive safety data in single-dose cohorts of healthy subjects and safety and efficacy data in the 60 mg and 180 mg single-dose cohorts in subjects with chronic HBV infection were reported in March 2020 and additional follow-on week 12 data for the 60 mg single-dose cohort were reported in May 2020. Week 12 data for the 90 mg single-dose cohort were reported in September 2020. The Company is dosing two 60 mg multi-dose cohorts of subjects with chronic HBV infection with dosing intervals of every four and eight weeks, respectively. Results from the 60 mg multi-dose cohort with a dosing interval of every four weeks and additional follow-up data on the 60 mg and 90 mg single-dose cohorts are expected to be disclosed as part of an oral presentation at the upcoming American Association for the Study of Liver Disease Conference (“AASLD”) in November. Separately, results from the 60 mg multi-dose cohort with a dosing interval of every eight weeks and a 90 mg single-dose cohort in HBV positive subjects are expected in the fourth quarter of 2020. Additionally, the Company is dosing two 90 mg multi-dose cohorts with chronic HBV infection with dosing intervals of every eight and twelve weeks, respectively; • AB-836, a next-generation capsid inhibitor product candidate currently advancing through CTA/IND-enabling studies, which the Company expects to be completed by the end of 2020; and • other compounds early in the development process, including oral compounds that inhibit PD-L1 and a next-generation oral HBV RNA destabilizer. The Company’s research and development activities and the commercialization of its products are dependent on its ability to successfully obtain adequate financing through a combination of financing activities and operations. The success of the Company is dependent on progressing its pipeline and subsequently obtaining the necessary regulatory approvals to bring its products to market and achieving profitable operations. It is not possible to predict either the outcome of the Company’s existing or future research and development programs or the Company’s ability to continue to fund these programs in the future, nor to predict whether it will be successful in obtaining the necessary regulatory approvals to bring its products to market. COVID-19 In December 2019, an outbreak of a novel strain of coronavirus (COVID-19) was identified in Wuhan, China. The virus continues to spread globally, has been declared a pandemic by the World Health Organization and has spread to nearly every country in the world. The impact of the pandemic has been, and will likely continue to be, extensive in many aspects of society. The pandemic has resulted in and will likely continue to result in significant disruptions to businesses. A number of countries and other jurisdictions around the world have implemented extreme measures in an attempt to slow the spread of the virus. These measures include the closing of businesses and requiring people to stay in their homes, the latter of which raises uncertainty regarding the ability to travel to hospitals in order to participate in clinical trials. Additional measures that have had, and will likely continue to have, a major impact on clinical development, at least in the near-term, include shortages and delays in the supply chain, and prohibitions in certain countries on enrolling subjects in new clinical trials. Despite the challenges of COVID-19, the Company has not had to alter its objectives for 2020. However, future disruptions related to the COVID-19

Significant accounting policies

Significant accounting policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Significant accounting policies	Significant accounting policies Basis of presentation These unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles for interim financial statements and accordingly, do not include all disclosures required for annual financial statements. These statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto for the year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (the “2019 Form 10-K”). These unaudited condensed consolidated financial statements reflect, in the opinion of management, all adjustments and reclassifications necessary to fairly present the Company’s financial position as of September 30, 2020, the Company’s results of operations for the three and nine months ended September 30, 2020 and the Company’s cash flows for the nine months ended September 30, 2020. The results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of the results for the full year. These unaudited condensed consolidated financial statements follow the same significant accounting policies as those described in the notes to the audited consolidated financial statements of the Company for the year ended December 31, 2019, except as described below under Recent Accounting Pronouncements. Principles of consolidation These unaudited condensed consolidated financial statements include the accounts of the Company and its two wholly-owned subsidiaries, Arbutus Biopharma Inc. (“Arbutus Inc.”) and Arbutus Biopharma US Holdings, Inc. All intercompany transactions and balances have been eliminated in consolidation. Net loss attributable to common shareholders per share The Company follows the two-class method when computing net loss attributable to common shareholders per share as the Company has issued Series A participating convertible preferred shares (the “Preferred Shares”), as further described in note 11, that meet the definition of participating securities. The Preferred Shares entitle the holders to participate in dividends but do not require the holders to participate in losses of the Company. Accordingly, if the Company reports a net loss attributable to holders of the Company’s common shares, net losses are not allocated to holders of the Preferred Shares. Net loss attributable to common shareholders per share is calculated based on the weighted average number of common shares outstanding. The calculation of diluted net loss attributable to common shareholders per share does not differ from the calculation of basic net loss attributable to common shareholders per share, as the effect of the Company’s dilutive potential common shares was anti-dilutive. During the nine months ended September 30, 2020 and 2019, potential common shares of 31.6 million and 28.2 million, respectively, consisting of the “if-converted” number of Preferred Shares and outstanding stock and Employee Stock Purchase Plan (“ESPP”) options, were excluded from the calculation of diluted net loss per common share because their inclusion would be anti-dilutive. Revenue recognition The Company recognizes revenue in accordance with ASC 606, Revenue from Contracts with Customers (”ASC 606”), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers under a five-step model: (i) identify 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 in the contract; and (v) recognize revenue when or as a performance obligation is satisfied. The Company generates revenue primarily through collaboration agreements and license agreements. Such agreements may require the Company to deliver various rights and/or services, including intellectual property rights or licenses and research and development services. Under such agreements, the Company is generally eligible to receive non-refundable upfront payments, funding for research and development services, milestone payments, and royalties. In contracts where the Company has more than one performance obligation to provide its customer with goods or services, each performance obligation is evaluated to determine whether it is distinct based on whether (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available and (ii) the good or service is separately identifiable from other promises in the contract. The consideration under the contract is then allocated between the distinct performance obligations based on their respective relative stand-alone selling prices. The estimated stand-alone selling price of each deliverable reflects the Company’s best estimate of what the selling price would be if the deliverable was regularly sold on a stand-alone basis and is determined by reference to market rates for the good or service when sold to others or by using an adjusted market assessment approach if the selling price on a stand-alone basis is not available. The consideration allocated to each distinct performance obligation is recognized as revenue when control is transferred to the customer for the related goods or services. Consideration associated with at-risk substantive performance milestones, including sales-based milestones, is recognized as revenue when it is probable that a significant reversal of the cumulative revenue recognized will not occur. Sales-based royalties received in connection with licenses of intellectual property are subject to a specific exception in the revenue standards, whereby the consideration is not included in the transaction price and recognized in revenue until the customer’s subsequent sales or usages occur. Segment information The Company operates as a single segment. Recent accounting pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial position or results of operations upon adoption. In June 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments

Fair value of financial instrum

Fair value of financial instruments	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair value of financial instruments	Fair value of financial instruments The Company measures certain financial instruments and other items at fair value. To determine the fair value, the Company uses the fair value hierarchy for inputs used in measuring fair value that maximize the use of observable inputs and minimize the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs are inputs market participants would use to value an asset or liability and are developed based on market data obtained from independent sources. Unobservable inputs are inputs based on assumptions about the factors market participants would use to value an asset or liability. The three levels of inputs that may be used to measure fair value are as follows: • Level 1 inputs are quoted market prices for identical instruments available in active markets. • Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability either directly or indirectly. If the asset or liability has a contractual term, the input must be observable for substantially the full term. An example includes quoted market prices for similar assets or liabilities in active markets. • Level 3 inputs are unobservable inputs for the asset or liability and will reflect management’s assumptions about market assumptions that would be used to price the asset or liability. Assets and liabilities are classified based on the lowest level of input that is significant to the fair value measurements. Changes in the observability of valuation inputs may result in a reclassification of levels for certain securities within the fair value hierarchy. The carrying values of cash and cash equivalents, investments in marketable securities, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to the immediate or short-term maturity of these financial instruments. To determine the fair value of the contingent consideration (note 8), the Company uses a probability weighted assessment of the likelihood the milestones would be met and the estimated timing of such payments, and then the potential contingent payments were discounted to their present value using a probability adjusted discount rate that reflects the early stage nature of the development program, time to complete the program development, and overall biotech indices. The Company determined the fair value of the contingent consideration was $3.3 million as of September 30, 2020 and the increase of $0.3 million has been recorded as a component of total operating expenses in the statement of operations and comprehensive loss for the nine months ended September 30, 2020. The assumptions used in the discounted cash flow model are level 3 inputs as defined above. The Company assessed the sensitivity of the fair value measurement to changes in these unobservable inputs, and determined that changes within a reasonable range would not result in a materially different assessment of fair value. The following table presents information about the Company’s assets and liabilities that are measured at fair value on a recurring basis, and indicates the level within the fair value hierarchy of the valuation techniques used to determine such fair value: Level 1 Level 2 Level 3 Total As of September 30, 2020 (in thousands) Assets Cash and cash equivalents $ 96,918 $ — $ — $ 96,918 Short-term investments 21,378 — — 21,378 Total 118,296 — — 118,296 Liabilities Liability-classified options — — 317 317 Contingent consideration — — 3,301 3,301 Total $ — $ — $ 3,618 $ 3,618 Level 1 Level 2 Level 3 Total As of December 31, 2019 (in thousands) Assets Cash and cash equivalents $ 31,799 $ — $ — $ 31,799 Short-term investments 59,035 — — 59,035 Total 90,834 — — 90,834 Liabilities Liability-classified stock option awards — — 253 253 Contingent consideration — — 2,953 2,953 Total $ — $ — $ 3,206 $ 3,206 The following table presents the changes in fair value of the Company’s liability-classified stock option awards: Liability at beginning of the period Fair value of liability-classified options exercised in the period Increase (decrease) in fair value of liability Liability at end of the period (in thousands) Nine Months Ended September 30, 2020 $ 253 $ — $ 64 $ 317 Nine Months Ended September 30, 2019 $ 479 $ — $ (393) $ 86 The following table presents the changes in fair value of the Company’s contingent consideration: Liability at beginning of the period Increase (decrease) in fair value of liability Liability at end of the period (in thousands) Nine Months Ended September 30, 2020 $ 2,953 $ 348 $ 3,301 Nine Months Ended September 30, 2019 $ 3,126 $ (121) $ 3,005

Investments in marketable secur

Investments in marketable securities	9 Months Ended
	Sep. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Investments in marketable securities	Investments in marketable securities Investments in marketable securities consisted of the following: Amortized Cost Gross Unrealized Gain (1) Gross Unrealized Loss (1) Fair Value As of September 30, 2020 (in thousands) Cash equivalents US government money market fund $ 65,327 $ — $ — $ 65,327 Total $ 65,327 $ — $ — $ 65,327 Investments in marketable securities US government agency bonds $ 11,300 $ 26 $ — $ 11,326 US government bonds 10,020 32 — 10,052 Total $ 21,320 $ 58 $ — $ 21,378 (1) Gross unrealized gain (loss) is pre-tax and is reported in other comprehensive loss. Amortized Cost Gross Unrealized Gain (1) Gross Unrealized Loss (1) Fair Value As of December 31, 2019 (in thousands) Cash equivalents US government money market fund $ 4,106 $ — $ — $ 4,106 US government agency bonds 1,511 — — 1,511 US treasury bills 1,499 — — 1,499 Total $ 7,116 $ — $ — $ 7,116 Investments in marketable securities US government agency bonds $ 19,863 $ 2 $ (1) $ 19,864 US treasury bills 15,926 2 (1) 15,927 US government bonds 23,246 — (2) 23,244 Total $ 59,035 $ 4 $ (4) $ 59,035 (1) Gross unrealized gain (loss) is pre-tax and is reported in other comprehensive loss. The contractual term to maturity of the $21.4 million of short-term marketable securities held by the Company as of September 30, 2020 is less than one year. As of December 31, 2019, the Company’s $59.0 million of marketable securities also had contractual maturities of less than one year.

Investment in Genevant

Investment in Genevant	9 Months Ended
	Sep. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
Investment in Genevant	Investment in Genevant In April 2018, Arbutus entered into an agreement with Roivant Sciences Ltd. (“Roivant”), its largest shareholder, to launch Genevant Sciences Ltd. (“Genevant”), a company focused on the discovery, development, and commercialization of a broad range of RNA-based therapeutics enabled by Arbutus’ lipid nanoparticle (“LNP”) and ligand conjugate delivery technologies. Arbutus licensed exclusive rights to its LNP and ligand conjugate delivery platforms to Genevant for RNA-based applications outside of HBV, except to the extent certain rights had already been licensed to other third parties. Arbutus retained all rights to its LNP and conjugate delivery platforms for HBV. Arbutus is entitled to receive tiered low single-digit royalties on future sales of Genevant products covered by the licensed patents. If Genevant sub-licenses the intellectual property licensed by Arbutus to Genevant, Arbutus would receive upon the commercialization of a product developed by such sub-licensee the lesser of (i) twenty percent of the revenue received by Genevant for such sublicensing and (ii) tiered low single-digit royalties on product sales by the sublicensee. On July 23, 2020, the United States Patent and Trademark Office before the Patent Trial and Appeal Board ("PTAB") announced their decision in Moderna Therapeutics, Inc.'s challenge of the validity of U.S. Patent 8,058,069 ("the '069 Patent"). In this decision, the PTAB determined no challenged claims were unpatentable. While Arbutus is the patent holder, this patent has been licensed to Genevant. The '069 Patent was included in the license agreement between Genevant and Arbutus. On July 31, 2020, Genevant was recapitalized through an equity investment and conversion of previously issued convertible debt securities held by Roivant. In addition, Arbutus participated in the recapitalization of Genevant with an investment of $2.5 million. Arbutus determined that this $2.5 million additional investment in Genevant represented the funding of prior losses and accordingly, the Company recorded the amount as an equity investment loss on the Condensed Consolidated Statements of Operations and Comprehensive Loss during the three months ended September 30, 2020. Following the recapitalization, Arbutus owned approximately 16% of the common equity of Genevant. In connection with the recapitalization, Genevant, Arbutus and Roivant entered into an Amended and Restated Shareholders Agreement that provides Roivant with substantial control of Genevant. Arbutus has a non-voting observer seat on Genevant’s Board of Directors. Due to Arbutus’ loss of significant influence with respect to Genevant as a result of the recapitalization, Arbutus discontinued the use of the equity method of accounting for its interest in Genevant. Following the recapitalization, Arbutus accounts for its interest in Genevant as equity securities without readily determinable fair values. Accordingly, an estimate of the fair value of the securities is based on the original cost less previously recognized equity method losses, less impairments, plus or minus changes resulting from observable price changes in orderly transactions for identical or a similar Genevant securities. As of September 30, 2020, the carrying value of Arbutus’ investment in Genevant was zero and Arbutus owned approximately 16% of the common equity of Genevant. Arbutus’ entitlement to receive future royalties or sublicensing revenue from Genevant was not impacted by the recapitalization.

Accounts payable and accrued li

Accounts payable and accrued liabilities	9 Months Ended
	Sep. 30, 2020
Payables and Accruals [Abstract]
Accounts payable and accrued liabilities	Accounts payable and accrued liabilities Accounts payable and accrued liabilities are comprised of the following: September 30, 2020 December 31, 2019 (in thousands) Trade accounts payable $ 852 $ 2,398 Research and development accruals 2,719 1,433 Professional fee accruals 447 809 Payroll accruals 2,844 2,314 Site consolidation accrual — 137 Other accrued liabilities 51 144 Total accounts payable and accrued liabilities $ 6,913 $ 7,235

Sale of future royalties

Sale of future royalties	9 Months Ended
	Sep. 30, 2020
Other Liabilities Disclosure [Abstract]
Sale of future royalties	Sale of future royalties On July 2, 2019, the Company entered into a Purchase and Sale Agreement (the “Agreement”) with the Ontario Municipal Employees Retirement System (or “OMERS”), pursuant to which the Company sold to OMERS part of its royalty interest on future global net sales of ONPATTRO® (Patisiran) (“ONPATTRO”), an RNAi therapeutic currently being sold by Alnylam Pharmaceuticals, Inc. (“Alnylam”). ONPATTRO utilizes Arbutus’ LNP technology, which was licensed to Alnylam pursuant to the Cross-License Agreement, dated November 12, 2012, by and between the Company and Alnylam (the “LNP License Agreement”). Under the terms of the LNP License Agreement, the Company is entitled to tiered royalty payments on global net sales of ONPATTRO ranging from 1.00% to 2.33% after offsets, with the highest tier applicable to annual net sales above $500 million. This royalty interest was sold to OMERS, effective as of January 1, 2019, for $20 million in gross proceeds before advisory fees. OMERS will retain this entitlement until it has received $30 million in royalties, at which point 100% of such royalty interest on future global net sales of ONPATTRO will revert to the Company. OMERS has assumed the risk of collecting up to $30 million of future royalty payments from Alnylam and Arbutus is not obligated to reimburse OMERS if they fail to collect any such future royalties. The $30 million in royalties to be collected by OMERS is accounted for as a liability, with the difference between the liability and the gross proceeds received accounted for as a discount. The discount, as well as $1.5 million of transaction costs, will be amortized as interest expense based on the projected balance of the liability as of the beginning of each period. Over the course of the Agreement, the actual interest rate will be affected by the amount and timing of royalty revenue recognized and changes in the timing of forecasted royalty revenue. On a quarterly basis, the Company will reassess the expected timing of the royalty revenue, recalculate the amortization and effective interest rate and adjust the accounting prospectively as needed. As of September 30, 2020, the effective annual interest rate was approximately 22%. The Company will recognize non-cash royalty revenue related to the sales of ONPATTRO during the term of the Agreement. As royalties are remitted to OMERS from Alnylam, the balance of the recognized liability will be effectively repaid over the life of the Agreement. From the inception of the royalty sale through September 30, 2020, the Company has recorded an aggregate of $3.7 million of non-cash royalty revenue for royalties earned by OMERS. There are a number of factors that could materially affect the amount and timing of royalty payments from Alnylam, none of which are within the Company’s control. During the three and nine months ended September 30, 2020, the Company recognized non-cash royalty revenue of $0.7 million and $2.0 million, respectively, and $1.1 million and $3.2 million of related non-cash interest expense, respectively. During the three and nine months ended September 30, 2019, the Company recognized non-cash royalty revenue of $0.5 million and $1.0 million, respectively, and $1.1 million of related non-cash interest expense during the three and nine months ended September 30, 2019. The table below shows the activity related to the net liability for 2020: Nine Months Ended September 30, 2020 (in thousands) Net liability related to sale of future royalties - beginning balance $ 18,992 Non-cash royalty revenue (2,041) Non-cash interest expense 3,166 Net liability related to sale of future royalties - ending balance $ 20,117 In addition to the royalty from the LNP License Agreement, the Company is also receiving a second, lower royalty interest on global net sales of ONPATTRO originating from a settlement agreement and subsequent license agreement with Acuitas Therapeutics, Inc. (“Acuitas”). The royalty from Acuitas has been retained by the Company and was not part of the royalty sale to OMERS.

Contingencies and commitments

Contingencies and commitments	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Contingencies and commitments	Contingencies and commitments Product development partnership with the Canadian Government The Company entered into a Technology Partnerships Canada (“TPC”) agreement with the Canadian Federal Government on November 12, 1999. Under this agreement, TPC agreed to fund 27% of the costs incurred by the Company, prior to March 31, 2004, in the development of certain oligonucleotide product candidates up to a maximum contribution from TPC of $7.2 million (C$9.3 million). The Company received a cumulative contribution of $2.7 million (C$3.7 million). In return for the funding provided by TPC, the Company agreed to pay royalties on the share of future licensing and product revenue, if any, that is received by the Company on certain non-RNAi oligonucleotide product candidates covered by the funding under the agreement. These royalties are payable until a certain cumulative payment amount is achieved or until a pre-specified date. In addition, until a cumulative amount equal to the funding actually received under the agreement has been paid to TPC, the Company agreed to pay 2.5% royalties on any royalties the Company receives on sales of Acrotech Biopharma LLC’s Marqibo® (formerly Spectrum Pharmaceuticals, Inc.). For each of the nine months ended September 30, 2020 and 2019, the Company earned royalties on Marqibo sales in the amount of $0.2 million. The resulting royalties payable by the Company to TPC were not material in either period. The cumulative amount paid or accrued up to September 30, 2020 was less than $0.1 million, resulting in the contingent amount due to TPC being $2.7 million (C$3.7 million). Arbitration with the University of British Columbia Certain early work on lipid nanoparticle delivery systems and related inventions was undertaken at the University of British Columbia (“UBC”), as well as by the Company that was subsequently assigned to UBC. These inventions are licensed to the Company by UBC under a license agreement, initially entered into in 1998 and amended in 2001, 2006 and 2007. The Company has granted sublicenses under the UBC license to certain third parties, including Alnylam. In November 2014, UBC filed a demand for arbitration against the Company and in January 2015, filed a Statement of Claim, which alleged entitlement to $3.5 million in allegedly unpaid royalties based on publicly available information, and an unspecified amount based on non-public information. UBC also sought interest and costs, including legal fees. The Company filed its Statement of Defense to UBC’s Statement of Claims, as well as a Counterclaim involving a patent application that the Company alleged UBC wrongly licensed to a third party. The proceedings were divided into three phases, with the first hearing taking place in June 2017. In the first phase, the arbitrator determined which agreements are sublicense agreements within UBC’s claim. Also in the first phase, UBC updated its alleged entitlement from $3.5 million originally claimed to seek $10.9 million in alleged unpaid royalties, plus interest arising from payments as early as 2008. The arbitrator also held in the first phase of the arbitration that the patent application that is the subject of the Counterclaim was not required to be licensed to the Company. The second phase of the arbitration took place in the second quarter of 2019. In August 2019, the arbitrator issued his decision for the second phase of the arbitration, awarding UBC $5.9 million, which includes interest of approximately $2.6 million. The Company paid the $5.9 million award to UBC in September 2019. The arbitrator also held that the third phase of the arbitration, which would address patent validity, should the Company choose to pursue a third phase, would not provide a defense to the award. An award for costs and attorneys’ fees is still to be determined. The Company has accrued $0.4 million for an estimate of a potential award for costs and attorneys’ fees as of September 30, 2020. Stock Purchase Agreement with Enantigen In October 2014, Arbutus Inc., our wholly-owned subsidiary, acquired all of the outstanding shares of Enantigen Therapeutics, Inc. (“Enantigen”) pursuant to a stock purchase agreement. Through this transaction, Arbutus Inc. acquired an HBV surface antigen secretion inhibitor program and a capsid assembly inhibitor program. Under the stock purchase agreement, Arbutus Inc. agreed to pay up to a total of $21.0 million to Enantigen’s selling stockholders upon the achievement of specified development and regulatory milestones for (a) the first two products that contain either a capsid compound or an HBV surface antigen compound that is covered by a patent acquired under this agreement, or (b) a capsid compound from an agreed upon list of compounds. The development milestones are tied to programs which are no longer under development by the Company, and therefore the contingency related to these milestones has been reduced to zero. An additional $102.5 million may also be paid to Enantigen’s selling stockholders related to the achievement of certain sales performance milestones in connection with the sale of the first commercialized product by Arbutus Inc. for the treatment of HBV, regardless of whether such product is based upon assets acquired under this agreement, and a low single-digit royalty on net sales of such first commercialized HBV product, up to a maximum royalty payment of $1.0 million that, if paid, would be offset against Arbutus Inc.’s milestone payment obligations.

Collaborations, contracts and l

Collaborations, contracts and licensing agreements	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Collaborations, contracts and licensing agreements	Collaborations, contracts and licensing agreements Revenue contracts are described in detail in the Overview section of Part II, Item 8, “Financial Statements and Supplementary Data” in the Company’s 2019 Form 10-K. Assembly BioSciences, Inc. In August 2020, the Company and Assembly BioSciences, Inc. (“Assembly”) entered into a clinical collaboration agreement to evaluate the Company’s proprietary GalNAC delivered RNAi therapeutic AB-729 in combination with Assembly’s lead HBV core inhibitor (capsid inhibitor) candidate vebicorvir and a standard-of-care nucleos(t)ide reverse transcriptase inhibitor (Nrtl) therapy for the treatment of patients with chronic HBV infection. The companies will share in the costs of the collaboration and the associated clinical trial is projected to initiate in the first half of 2021. The Company incurred no costs related to the collaboration during the three months ended September 30, 2020. Alnylam Pharmaceuticals, Inc. and Acuitas Therapeutics, Inc. The Company has two royalty entitlements to Alnylam’s global net sales of ONPATTRO. In 2012, the Company entered into a license agreement with Alnylam that entitles Alnylam to develop and commercialize products with the Company’s LNP technology. Alnylam’s ONPATTRO, which represents the first approved application of the Company’s LNP technology, was approved by the United States Food and Drug Administration (“FDA”) and the European Medicines Agency (“EMA”) during the third quarter of 2018 and was launched by Alnylam immediately upon approval in the United States. Under the terms of this license agreement, the Company is entitled to tiered royalty payments on global net sales of ONPATTRO ranging from 1.00% - 2.33% after offsets, with the highest tier applicable to annual net sales above $500 million. This royalty interest was sold to OMERS, effective as of January 1, 2019, for $20 million in gross proceeds before advisory fees. OMERS will retain this entitlement until it has received $30 million in royalties, at which point 100% of this royalty entitlement on future global net sales of ONPATTRO will revert back to the Company. OMERS has assumed the risk of collecting up to $30 million of future royalty payments from Alnylam and the Company is not obligated to reimburse OMERS if they fail to collect any such future royalties. If this royalty entitlement reverts to the Company, it has the potential to provide an active royalty stream or to be otherwise monetized again in full or in part. The Company also has rights to a second, lower royalty interest on global net sales of ONPATTRO originating from a settlement agreement and subsequent license agreement with Acuitas. This royalty entitlement from Acuitas has been retained by the Company and was not part of the royalty entitlement sale to OMERS. Revenues are summarized in the following table: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) (in thousands) Revenue from collaborations and licenses Acuitas Therapeutics, Inc. $ 774 $ 516 $ 2,288 $ 1,161 Gritstone Oncology, Inc. — 1,722 — 1,789 Other milestone and royalty payments 54 362 199 464 Non-cash royalty revenue Alnylam Pharmaceuticals, Inc. 695 461 2,041 979 Total revenue $ 1,523 $ 3,061 $ 4,528 4,393

Stockholders_ equity

Stockholders’ equity	9 Months Ended
	Sep. 30, 2020
Stockholders' Equity Note [Abstract]
Stockholders’ equity	Stockholders’ equity Open Market Sales Agreement In December 2018, the Company entered into an Open Market Sale Agreement with Jefferies LLC (“Jefferies”) (the “Sale Agreement”), under which it could issue and sell common shares, from time to time, for an aggregate sales price of up to $50.0 million. In December 2019, the Company entered into an amendment to the Sale Agreement with Jefferies (the “2019 Amendment”) in connection with the filing of a shelf registration statement on Form S-3 (File No. 333-235674), filed with the SEC on December 23, 2019 (the “Shelf Registration Statement”). The 2019 Amendment revised the original Sale Agreement to reflect that the Company could sell its common shares, without par value, from time to time, for an aggregate sales price of up to $50 million, under the Shelf Registration Statement. In July 2020, the Company fully utilized the remaining availability under the Sale Agreement, as amended by the 2019 Amendment. In August 2020, the Company entered into a new amendment to the Sale Agreement (the “2020 Amendment”) with Jefferies. Pursuant to the 2020 Amendment, the Company can issue and sell common shares, from time to time, for an aggregate sales price of up to $75 million under the Sale Agreement, as amended. For the nine months ended September 30, 2019, the Company issued 1,208,090 common shares pursuant to the Sale Agreement resulting in net proceeds of approximately $5.2 million. There were no shares issued under the Sale Agreement during the three months ended September 30, 2019. During the three and nine months ended September 30, 2020, the Company issued 13,258,096 and 19,696,361 common shares pursuant to the Sale Agreement, as amended, resulting in net proceeds of approximately $48.8 million and $66.1 million, respectively. As of September 30, 2020, there was approximately $62.3 million available under the Sale Agreement, as amended. Stock-based compensation The table below summarizes information about the Company’s stock based compensation for the three and nine months ended September 30, 2020 and 2019 and the expense recognized in the condensed consolidated statements of operations: Three Months Ended September 30, 2020 Three Months Ended September 30, 2019 Nine Months Ended September 30, 2020 Nine Months Ended September 30, 2019 (in thousands, except share and per share data) Options granted during period 188,600 242,400 2,856,150 3,018,000 Weighted average exercise price $ 2.25 $ 1.57 $ 3.21 $ 3.41 Research and development $ 808 $ 817 $ 2,341 $ 2,361 General and administrative 880 699 2,389 4,461 Total stock compensation expense $ 1,688 $ 1,516 $ 4,730 $ 6,822 Awards with performance conditions are expensed when it is probable that the performance condition will be achieved. For each of the three and nine months ended September 30, 2020, $0.3 million was expensed for stock option awards with performance conditions. These expenses are included in the table above. Employee Stock Purchase Plan In May 2020, the Company’s stockholders approved the 2020 Employee Stock Purchase Plan which became effective on May 28, 2020. A total of 1.5 million common shares were reserved for issuance under the ESPP. Company employees contribute funds via payroll deductions, which are used to buy Company common shares at a discount of up to 15% based on the lower of the price at the start of the offering period and at the end of the relevant purchase period within such offering period. The initial offering period under the ESPP is September 1, 2020 through August 31, 2021 with purchase dates set on February 26, 2021 and August 31, 2021. All 1.5 million common shares remained available for future issuance under the plan at September 30, 2020. For the three and nine months ended September 30, 2020, the Company recognized less than $0.1 million of stock-based compensation expense related to the ESPP, which is included in the table above. Series A Preferred Shares In October 2017, the Company entered into a subscription agreement with Roivant for the sale of 1,164,000 Preferred Shares for gross proceeds of $116.4 million. These Preferred Shares are non-voting and accrue an 8.75% per annum coupon in the form of additional Preferred Shares, compounded annually, until October 16, 2021, at which time all the Preferred Shares will be subject to mandatory conversion into common shares (subject to limited exceptions in the event of certain fundamental corporate transactions relating to Arbutus’s capital structure or assets, which would permit earlier conversion at Roivant’s option). The conversion price is $7.13 per share, which will result in the Preferred Shares being converted into approximately 23 million common shares. After conversion of the Preferred Shares into common shares, based on the number of common shares outstanding as of September 30, 2020, Roivant will hold approximately 36% of the Company’s common shares. Roivant agreed to a four four The Company records the Preferred Shares wholly as equity under ASC 480, Distinguishing Liabilities From Equity, with no bifurcation of the conversion feature from the host contract, given that the Preferred Shares cannot be cash settled and the redemption features are within the Company’s control, which include a fixed conversion ratio with predetermined timing and proceeds. The Company accrues for the 8.75% per annum compounding coupon at each reporting period end date as an increase to preferred share capital, and an increase to deficit (see Condensed Consolidated Statement of Stockholders’ Equity).

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions On July 31, 2020, Genevant was recapitalized through an equity investment and conversion of previously issued convertible debt securities held by Roivant. In addition, Arbutus participated in the recapitalization with an investment of $2.5 million. Following the recapitalization, Arbutus owned approximately 16% of the common equity of Genevant. See note 5 for more information. Through the first quarter of 2019, the Company purchased certain research and development services from Genevant. These services were billed at agreed hourly rates and were reflective of market rates for such services. The total cost of these services during 2019 was less than $0.1 million, which was included in the Condensed Consolidated Statement of Operations under research and development. There were no such costs incurred during 2020. Conversely, Genevant purchased certain administrative and transitional services from the Company totaling less than $35 thousand for each of the three and nine months ended September 30, 2020. The total income from these services was $40 thousand and $284 thousand for the three and nine months ended September 30, 2019. This income is netted against research and development expenses in the condensed consolidated statements of operations. In addition, during 2019 Genevant had a sublease for 17,900 square feet in the Company’s Burnaby facility. Sublease income from Genevant was $21 thousand and $145 thousand for the three and nine months ended September 30, 2019, and was netted against site consolidation costs and lease liability. The Company’s Burnaby facility lease and the corresponding sublease to Genevant expired on July 31, 2019.

Significant accounting polici_2

Significant accounting policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation These unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles for interim financial statements and accordingly, do not include all disclosures required for annual financial statements. These statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto for the year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (the “2019 Form 10-K”). These unaudited condensed consolidated financial statements reflect, in the opinion of management, all adjustments and reclassifications necessary to fairly present the Company’s financial position as of September 30, 2020, the Company’s results of operations for the three and nine months ended September 30, 2020 and the Company’s cash flows for the nine months ended September 30, 2020. The results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of the results for the full year. These unaudited condensed consolidated financial statements follow the same significant accounting policies as those described in the notes to the audited consolidated financial statements of the Company for the year ended December 31, 2019, except as described below under Recent Accounting Pronouncements.
Principles of consolidation	Principles of consolidation These unaudited condensed consolidated financial statements include the accounts of the Company and its two wholly-owned subsidiaries, Arbutus Biopharma Inc. (“Arbutus Inc.”) and Arbutus Biopharma US Holdings, Inc. All intercompany transactions and balances have been eliminated in consolidation.
Net loss attributable to common shareholders per share	Net loss attributable to common shareholders per share The Company follows the two-class method when computing net loss attributable to common shareholders per share as the Company has issued Series A participating convertible preferred shares (the “Preferred Shares”), as further described in note 11, that meet the definition of participating securities. The Preferred Shares entitle the holders to participate in dividends but do not require the holders to participate in losses of the Company. Accordingly, if the Company reports a net loss attributable to holders of the Company’s common shares, net losses are not allocated to holders of the Preferred Shares.
Revenue recognition	Revenue recognition The Company recognizes revenue in accordance with ASC 606, Revenue from Contracts with Customers (”ASC 606”), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers under a five-step model: (i) identify 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 in the contract; and (v) recognize revenue when or as a performance obligation is satisfied. The Company generates revenue primarily through collaboration agreements and license agreements. Such agreements may require the Company to deliver various rights and/or services, including intellectual property rights or licenses and research and development services. Under such agreements, the Company is generally eligible to receive non-refundable upfront payments, funding for research and development services, milestone payments, and royalties. In contracts where the Company has more than one performance obligation to provide its customer with goods or services, each performance obligation is evaluated to determine whether it is distinct based on whether (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available and (ii) the good or service is separately identifiable from other promises in the contract. The consideration under the contract is then allocated between the distinct performance obligations based on their respective relative stand-alone selling prices. The estimated stand-alone selling price of each deliverable reflects the Company’s best estimate of what the selling price would be if the deliverable was regularly sold on a stand-alone basis and is determined by reference to market rates for the good or service when sold to others or by using an adjusted market assessment approach if the selling price on a stand-alone basis is not available. The consideration allocated to each distinct performance obligation is recognized as revenue when control is transferred to the customer for the related goods or services. Consideration associated with at-risk substantive performance milestones, including sales-based milestones, is recognized as revenue when it is probable that a significant reversal of the cumulative revenue recognized will not occur. Sales-based royalties received in connection with licenses of intellectual property are subject to a specific exception in the revenue standards, whereby the consideration is not included in the transaction price and recognized in revenue until the customer’s subsequent sales or usages occur.
Segment information	Segment informationThe Company operates as a single segment.
Recent accounting pronouncements	Recent accounting pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial position or results of operations upon adoption. In June 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments
Fair value of financial instruments	Fair value of financial instruments The Company measures certain financial instruments and other items at fair value. To determine the fair value, the Company uses the fair value hierarchy for inputs used in measuring fair value that maximize the use of observable inputs and minimize the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs are inputs market participants would use to value an asset or liability and are developed based on market data obtained from independent sources. Unobservable inputs are inputs based on assumptions about the factors market participants would use to value an asset or liability. The three levels of inputs that may be used to measure fair value are as follows: • Level 1 inputs are quoted market prices for identical instruments available in active markets. • Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability either directly or indirectly. If the asset or liability has a contractual term, the input must be observable for substantially the full term. An example includes quoted market prices for similar assets or liabilities in active markets. • Level 3 inputs are unobservable inputs for the asset or liability and will reflect management’s assumptions about market assumptions that would be used to price the asset or liability. Assets and liabilities are classified based on the lowest level of input that is significant to the fair value measurements. Changes in the observability of valuation inputs may result in a reclassification of levels for certain securities within the fair value hierarchy. The carrying values of cash and cash equivalents, investments in marketable securities, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to the immediate or short-term maturity of these financial instruments.

Fair value of financial instr_2

Fair value of financial instruments (Tables)	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Assets and liabilities measured at fair value on a recurring basis	The following table presents information about the Company’s assets and liabilities that are measured at fair value on a recurring basis, and indicates the level within the fair value hierarchy of the valuation techniques used to determine such fair value: Level 1 Level 2 Level 3 Total As of September 30, 2020 (in thousands) Assets Cash and cash equivalents $ 96,918 $ — $ — $ 96,918 Short-term investments 21,378 — — 21,378 Total 118,296 — — 118,296 Liabilities Liability-classified options — — 317 317 Contingent consideration — — 3,301 3,301 Total $ — $ — $ 3,618 $ 3,618 Level 1 Level 2 Level 3 Total As of December 31, 2019 (in thousands) Assets Cash and cash equivalents $ 31,799 $ — $ — $ 31,799 Short-term investments 59,035 — — 59,035 Total 90,834 — — 90,834 Liabilities Liability-classified stock option awards — — 253 253 Contingent consideration — — 2,953 2,953 Total $ — $ — $ 3,206 $ 3,206
Changes in fair value of liability option	The following table presents the changes in fair value of the Company’s liability-classified stock option awards: Liability at beginning of the period Fair value of liability-classified options exercised in the period Increase (decrease) in fair value of liability Liability at end of the period (in thousands) Nine Months Ended September 30, 2020 $ 253 $ — $ 64 $ 317 Nine Months Ended September 30, 2019 $ 479 $ — $ (393) $ 86
Schedule of changes in fair value of contingent consideration		The following table presents the changes in fair value of the Company’s contingent consideration: Liability at beginning of the period Increase (decrease) in fair value of liability Liability at end of the period (in thousands) Nine Months Ended September 30, 2020 $ 2,953 $ 348 $ 3,301 Nine Months Ended September 30, 2019 $ 3,126 $ (121) $ 3,005

Investments in marketable sec_2

Investments in marketable securities (Tables)	9 Months Ended
	Sep. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Marketable securities	Investments in marketable securities consisted of the following: Amortized Cost Gross Unrealized Gain (1) Gross Unrealized Loss (1) Fair Value As of September 30, 2020 (in thousands) Cash equivalents US government money market fund $ 65,327 $ — $ — $ 65,327 Total $ 65,327 $ — $ — $ 65,327 Investments in marketable securities US government agency bonds $ 11,300 $ 26 $ — $ 11,326 US government bonds 10,020 32 — 10,052 Total $ 21,320 $ 58 $ — $ 21,378 (1) Gross unrealized gain (loss) is pre-tax and is reported in other comprehensive loss. Amortized Cost Gross Unrealized Gain (1) Gross Unrealized Loss (1) Fair Value As of December 31, 2019 (in thousands) Cash equivalents US government money market fund $ 4,106 $ — $ — $ 4,106 US government agency bonds 1,511 — — 1,511 US treasury bills 1,499 — — 1,499 Total $ 7,116 $ — $ — $ 7,116 Investments in marketable securities US government agency bonds $ 19,863 $ 2 $ (1) $ 19,864 US treasury bills 15,926 2 (1) 15,927 US government bonds 23,246 — (2) 23,244 Total $ 59,035 $ 4 $ (4) $ 59,035 (1) Gross unrealized gain (loss) is pre-tax and is reported in other comprehensive loss.

Accounts payable and accrued _2

Accounts payable and accrued liabilities (Tables)	9 Months Ended
	Sep. 30, 2020
Payables and Accruals [Abstract]
Schedule of accounts payable and accrued liabilities	Accounts payable and accrued liabilities are comprised of the following: September 30, 2020 December 31, 2019 (in thousands) Trade accounts payable $ 852 $ 2,398 Research and development accruals 2,719 1,433 Professional fee accruals 447 809 Payroll accruals 2,844 2,314 Site consolidation accrual — 137 Other accrued liabilities 51 144 Total accounts payable and accrued liabilities $ 6,913 $ 7,235

Sale of future royalties (Table

Sale of future royalties (Tables)	9 Months Ended
	Sep. 30, 2020
Other Liabilities Disclosure [Abstract]
Schedule of activity related to the net liability from inception of the Agreement	The table below shows the activity related to the net liability for 2020: Nine Months Ended September 30, 2020 (in thousands) Net liability related to sale of future royalties - beginning balance $ 18,992 Non-cash royalty revenue (2,041) Non-cash interest expense 3,166 Net liability related to sale of future royalties - ending balance $ 20,117

Collaborations, contracts and_2

Collaborations, contracts and licensing agreements (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Summary of collaborations	Revenues are summarized in the following table: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 (in thousands) (in thousands) Revenue from collaborations and licenses Acuitas Therapeutics, Inc. $ 774 $ 516 $ 2,288 $ 1,161 Gritstone Oncology, Inc. — 1,722 — 1,789 Other milestone and royalty payments 54 362 199 464 Non-cash royalty revenue Alnylam Pharmaceuticals, Inc. 695 461 2,041 979 Total revenue $ 1,523 $ 3,061 $ 4,528 4,393

Stockholders_ equity (Tables)

Stockholders’ equity (Tables)	9 Months Ended
	Sep. 30, 2020
Stockholders' Equity Note [Abstract]
Schedule of stock based compensation expense	The table below summarizes information about the Company’s stock based compensation for the three and nine months ended September 30, 2020 and 2019 and the expense recognized in the condensed consolidated statements of operations: Three Months Ended September 30, 2020 Three Months Ended September 30, 2019 Nine Months Ended September 30, 2020 Nine Months Ended September 30, 2019 (in thousands, except share and per share data) Options granted during period 188,600 242,400 2,856,150 3,018,000 Weighted average exercise price $ 2.25 $ 1.57 $ 3.21 $ 3.41 Research and development $ 808 $ 817 $ 2,341 $ 2,361 General and administrative 880 699 2,389 4,461 Total stock compensation expense $ 1,688 $ 1,516 $ 4,730 $ 6,822

Significant accounting polici_3

Significant accounting policies (Details) shares in Millions	9 Months Ended
	Sep. 30, 2020numberOfSegmentssubsidiaryshares	Sep. 30, 2019shares
Accounting Policies [Abstract]
Number of wholly-owed subsidiaries | subsidiary	2
Anti-dilutive common shares excluded from calculation of loss per common share (in shares) | shares	31.6	28.2
Number of segments | numberOfSegments	1

Fair value of financial instr_3

Fair value of financial instruments - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair value of contingent consideration	$ 3,301	$ 3,005	$ 2,953	$ 3,126
Increase (decrease) in fair value of contingent consideration	$ 348	$ (121)

Fair value of financial instr_4

Fair value of financial instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Liabilities
Contingent consideration	$ 3,301	$ 2,953	$ 3,005	$ 3,126
Recurring
Assets
Cash and cash equivalents	96,918	31,799
Short-term investments	21,378	59,035
Total	118,296	90,834
Liabilities
Liability-classified options	317	253
Contingent consideration	3,301	2,953
Total	3,618	3,206
Recurring | Level 1
Assets
Cash and cash equivalents	96,918	31,799
Short-term investments	21,378	59,035
Total	118,296	90,834
Liabilities
Liability-classified options	0	0
Contingent consideration	0	0
Total	0	0
Recurring | Level 2
Assets
Cash and cash equivalents	0	0
Short-term investments	0	0
Total	0	0
Liabilities
Liability-classified options	0	0
Contingent consideration	0	0
Total	0	0
Recurring | Level 3
Assets
Cash and cash equivalents	0	0
Short-term investments	0	0
Total	0	0
Liabilities
Liability-classified options	317	253
Contingent consideration	3,301	2,953
Total	$ 3,618	$ 3,206

Fair value of financial instr_5

Fair value of financial instruments - Changes in Fair Value of Liabilities-Classified as Stock Option (Details) - Liability classified stock options - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Fair Value, Liabilities Measured on Recurring Basis [Roll Forward]
Liability at beginning of the period	$ 253	$ 479
Fair value of liability-classified options exercised in the period	0	0
Increase (decrease) in fair value of liability	64	(393)
Liability at end of the period	$ 317	$ 86

Fair value of financial instr_6

Fair value of financial instruments - Changes in Fair Value of Contingent Consideration (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Fair Value, Liabilities Measured on Recurring Basis [Roll Forward]
Liability at beginning of the period	$ 2,953	$ 3,126
Increase (decrease) in fair value of liability	348	(121)
Liability at end of the period	$ 3,301	$ 3,005

Investments in marketable sec_3

Investments in marketable securities- Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 21,400	$ 59,000
Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	65,327	7,116
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	65,327	7,116
Cash equivalents | US government money market fund
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	65,327	4,106
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	65,327	4,106
Cash equivalents | US government agency bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		1,511
Gross Unrealized Gain		0
Gross Unrealized Loss		0
Fair Value		1,511
Cash equivalents | US treasury bills
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		1,499
Gross Unrealized Gain		0
Gross Unrealized Loss		0
Fair Value		1,499
Investments in marketable securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	21,320	59,035
Gross Unrealized Gain	58	4
Gross Unrealized Loss	0	(4)
Fair Value	21,378	59,035
Investments in marketable securities | US government agency bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	11,300	19,863
Gross Unrealized Gain	26	2
Gross Unrealized Loss	0	(1)
Fair Value	11,326	19,864
Investments in marketable securities | US treasury bills
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		15,926
Gross Unrealized Gain		2
Gross Unrealized Loss		(1)
Fair Value		15,927
Investments in marketable securities | US government bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,020	23,246
Gross Unrealized Gain	32	0
Gross Unrealized Loss	0	(2)
Fair Value	$ 10,052	$ 23,244

Investments in marketable sec_4

Investments in marketable securities - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Marketable Securities [Line Items]
Investments in marketable securities, current	$ 21,400,000		$ 21,400,000		$ 59,000,000
Investments in marketable securities
Marketable Securities [Line Items]
Investments in marketable securities, current	21,378,000		21,378,000		$ 59,035,000
Realized gains or losses	$ 0	$ 0	$ 0	$ 0

Investment in Genevant (Details

Investment in Genevant (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jul. 31, 2020
Schedule of Equity Method Investments [Line Items]
Investment					$ 2,500,000
Equity investment loss	$ (2,545,000)	$ (3,512,000)	$ (2,545,000)	$ (11,497,000)
Equity investment	0		$ 0
Genevant
Schedule of Equity Method Investments [Line Items]
Investment					$ 2,500,000
Equity investment loss	$ 2,500,000
Ownership interest in equity method investment (as a percentage)	16.00%		16.00%		16.00%

Accounts payable and accrued _3

Accounts payable and accrued liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Trade accounts payable	$ 852	$ 2,398
Research and development accruals	2,719	1,433
Professional fee accruals	447	809
Payroll accruals	2,844	2,314
Site consolidation accrual	0	137
Other accrued liabilities	51	144
Total accounts payable and accrued liabilities	$ 6,913	$ 7,235

Sale of future royalties - Narr

Sale of future royalties - Narrative (Details) - USD ($)	Jul. 02, 2019	Jan. 01, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020
Other Liabilities Disclosure [Line Items]
Royalty guarantees commitments percentage					2.50%
Non-cash royalty revenue					$ 2,041,000	$ 979,000
Non-cash interest expense					$ 3,166,000
OMERS
Other Liabilities Disclosure [Line Items]
Annual royalty revenue	$ 500,000,000
Gross proceeds from sale of royalty interest. before advisory fees		$ 20,000,000
Entitlement of royalties to be received	$ 30,000,000
Royalty guarantees commitments percentage	100.00%
Future royalty payments	$ 30,000,000
Transaction costs on sale of royalties	$ 1,500,000
Effective annual interest rate on royalty liability					22.00%
Non-cash royalty revenue			$ (700,000)	$ 500,000	$ 2,000,000	1,000,000	$ 3,700,000
Non-cash interest expense			$ 1,100,000	$ 1,100,000	$ 3,200,000	$ 1,100,000
OMERS | Minimum
Other Liabilities Disclosure [Line Items]
Royalty, interest sold, percentage	1.00%
OMERS | Maximum
Other Liabilities Disclosure [Line Items]
Royalty, interest sold, percentage	2.33%

Sale of future royalties - Liab

Sale of future royalties - Liability Activity (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Liability Related To Sale Of Future Royalties [Roll Forward]
Net liability related to sale of future royalties - beginning balance	$ 18,992
Non-cash royalty revenue	(2,041)
Non-cash interest expense	3,166
Net liability related to sale of future royalties - ending balance	$ 20,117

Contingencies and commitments (

Contingencies and commitments (Details) $ in Millions

1 Months Ended

9 Months Ended

53 Months Ended

Sep. 30, 2019USD ($)

Aug. 31, 2019USD ($)

Jun. 30, 2017USD ($)Legal_proceedings

Jan. 31, 2015USD ($)

Sep. 30, 2020USD ($)

Sep. 30, 2020CAD ($)

Sep. 30, 2019USD ($)

Mar. 31, 2004USD ($)

Mar. 31, 2004CAD ($)

Sep. 30, 2020CAD ($)

Dec. 31, 2019USD ($)

Dec. 31, 2018USD ($)

Oct. 31, 2014USD ($)product

Contingencies and Commitments [Line Items]

Percent of costs funded by TPC

27.00%

27.00%

Maximum contribution for product

$ 7,200,000

$ 9.3

Cumulative contribution for product

$ 2,700,000

$ 3.7

Royalty guarantees commitments percentage

2.50%

2.50%

Estimate of potential arbitration award for costs and attorney's fees

$ 400,000

Fair value of contingent consideration

$ 3,005,000

3,301,000

$ 3,005,000

$ 2,953,000

$ 3,126,000

Recurring

Contingencies and Commitments [Line Items]

Fair value of contingent consideration

3,301,000

$ 2,953,000

Arbutus Inc. | Enantigen

Contingencies and Commitments [Line Items]

Business combination, high end of payment upon achievement of certain triggering events

$ 21,000,000

Number of products covered by patent acquired under the agreement | product

2

Arbitration with the University of British Columbia

Contingencies and Commitments [Line Items]

Loss contingency, damages sought for allegedly unpaid royalties

$ 10,900,000

$ 3,500,000

Number of legal proceedings | Legal_proceedings

3

Arbitration settlement, amount awarded to other party

$ 5,900,000

Arbitration settlement interest

$ 2,600,000

Arbitration settlement payment

$ 5,900,000

Blumberg and Drexel | Enantigen | Recurring

Contingencies and Commitments [Line Items]

Fair value of contingent consideration

3,300,000

$ 0

Blumberg and Drexel | Arbutus Inc.

Contingencies and Commitments [Line Items]

Development and regulatory milestones payment per licensed compound series, maximum

102,500,000

Development and regulatory milestones payment per royalty, maximum

$ 1,000,000

Royalty

Contingencies and Commitments [Line Items]

Royalties paid or accrued

100,000

Contractual obligation

2,700,000

$ 3.7

Royalty | Acrotech Biopharma

Contingencies and Commitments [Line Items]

Royalties earned

$ 200,000

$ 200,000

Collaborations, contracts and_3

Collaborations, contracts and licensing agreements (Details) - USD ($)	Jul. 02, 2019	Jan. 01, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty guarantees commitments percentage					2.50%
Revenue			$ 1,523,000	$ 3,061,000	$ 4,528,000	$ 4,393,000
Assembly Biosciences, Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Costs related to collaboration			0
OMERS
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Annual royalty revenue	$ 500,000,000
Gross proceeds from sale of royalty interest. before advisory fees		$ 20,000,000
Entitlement of royalties to be received	$ 30,000,000
Royalty guarantees commitments percentage	100.00%
Future royalty payments	$ 30,000,000
OMERS | Minimum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty, interest sold, percentage	1.00%
OMERS | Maximum
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Royalty, interest sold, percentage	2.33%
Revenue from collaborations and licenses | Acuitas Therapeutics, Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue			774,000	516,000	2,288,000	1,161,000
Revenue from collaborations and licenses | Gritstone Oncology, Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue			0	1,722,000	0	1,789,000
Revenue from collaborations and licenses | Other milestone and royalty payments
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue			54,000	362,000	199,000	464,000
Non-cash royalty revenue
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue			696,000	461,000	2,041,000	979,000
Non-cash royalty revenue | Alnylam Pharmaceuticals, Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue			$ 695,000	$ 461,000	$ 2,041,000	$ 979,000

Stockholders_ equity - Narrativ

Stockholders’ equity - Narrative (Details) - USD ($)	1 Months Ended		3 Months Ended						9 Months Ended
	Jan. 31, 2018	Oct. 31, 2017	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Aug. 31, 2020	May 28, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Proceeds from issuance of shares under the agreement									$ 66,120,000	$ 4,725,000
Stock option awards expense			$ 300,000						$ 300,000
Number of shares reserved for issuance			1,500,000						1,500,000			1,500,000
Common shares, discount rate												$ 0.15
Stock-based compensation related to ESPP			$ 100,000						$ 100,000
Issuance of common shares pursuant to the agreement			$ 48,760,000	$ 5,045,000	$ 12,315,000		$ 2,477,000	$ 2,248,000
Preferred Shares
Class of Stock [Line Items]
Shares issued (in shares)		1,164,000
Roivant Sciences Ltd
Class of Stock [Line Items]
Ownership percentage by noncontrolling owners after conversion			36.00%						36.00%
Maximum ownership percentage by noncontrolling owners		49.99%
Proceeds from sale of stock	$ 66,400,000	$ 50,000,000
Roivant Sciences Ltd | Convertible Preferred Stock
Class of Stock [Line Items]
Issuance of common shares pursuant to the agreement		$ 116,400,000
Preferred stock dividend rate as a percent		8.75%							8.75%
Preferred stated value (in dollars per share)		$ 7.13
Number of common shares to be issued upon conversion of convertible preferred stock		23,000,000
Investment commitment period		4 years
Open Market Sale Agreement | Jefferies LLC | Common Shares
Class of Stock [Line Items]
Aggregate sale price of common shares under agreement			$ 62,300,000						$ 62,300,000		$ 75,000,000		$ 50,000,000	$ 50,000,000
Number of shares issued under agreement (in sales)			13,258,096			0			19,696,361	1,208,090
Proceeds from issuance of shares under the agreement			$ 48,800,000						$ 66,100,000	$ 5,200,000

Stockholders_ equity - Stock-ba

Stockholders’ equity - Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price (in USD per share)	$ 2.25	$ 1.57	$ 3.21	$ 3.41
Allocated share-based compensation expense	$ 1,688	$ 1,516	$ 4,730	$ 6,822
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	808	817	2,341	2,361
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 880	$ 699	$ 2,389	$ 4,461
Arbutus Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted during period (in shares)	188,600	242,400	2,856,150	3,018,000

Related Party Transactions (Det

Related Party Transactions (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)ft²	Jul. 31, 2020USD ($)
Related Party Transaction [Line Items]
Investment						$ 2,500,000
Genevant Sciences Corporation
Related Party Transaction [Line Items]
Investment						$ 2,500,000
Ownership interest in equity method investment (as a percentage)	16.00%		16.00%			16.00%
Genevant Sciences Corporation | Equity Method Investee | Research and development services
Related Party Transaction [Line Items]
Expenses from transactions with related party			$ 0		$ 100,000
Genevant Sciences Corporation | Equity Method Investee | Administrative and transitional services
Related Party Transaction [Line Items]
Expenses from transactions with related party	$ 35,000		$ 35,000
Income from related party		$ 40,000		$ 284,000
Genevant Sciences Corporation | Equity Method Investee | Sublease, Burnaby facility
Related Party Transaction [Line Items]
Sublease income		$ 21,000		$ 145,000
Area of sublease facility | ft²					17,900