8-K: Arbutus Q3 2025: Imdusiran Progress, Strong Cash, LNP Litigation

Arbutus Biopharma reported strong Q3 2025 financial results, positive imdusiran clinical data, and favorable progress in its LNP patent litigation against Moderna and Pfizer/BioNTech.

Summary

• Cash, cash equivalents, and marketable securities totaled $93.7 million as of September 30, 2025, down from $122.6 million at December 31, 2024.
• Used $35.0 million in operating activities during the nine months ended September 30, 2025, which included one-time payments related to restructuring efforts.
• 46% of Phase 2a imdusiran patients (48 out of 105) met criteria to discontinue all treatment or remained off nucleos(t)ide analogue (NA) therapy for at least 48 weeks.
• 94% of long-term follow-up patients (17 out of 18) remain off all treatment for up to 2+ years.
• 100% of HBV DNA positive patients in Phase 1b achieved HBV DNA levels below quantification after only 18 weeks of imdusiran and NA therapy.
• The Moderna U.S. litigation jury trial is scheduled for March 2026.
• A favorable claim construction ruling in the Pfizer-BioNTech litigation was issued in September 2025.
• Net loss for the third quarter ended September 30, 2025, was $7.7 million, or $0.04 per basic and diluted common share, compared to a net loss of $19.7 million, or $0.10 per share, for the same period in 2024.
• Total revenue for Q3 2025 was $0.5 million, a decrease of $0.8 million from $1.3 million in Q3 2024, primarily due to a decline in Alnylam's sales of ONPATTRO.
• Research and development expenses decreased by $8.5 million to $5.8 million in Q3 2025 due to cost savings from streamlining efforts.
• General and administrative expenses decreased to $3.0 million in Q3 2025 due to cost-cutting efforts.

Sentiment

Score: 8

Explanation: The company demonstrated strong operational efficiency with a significantly reduced net loss and controlled expenses. The clinical data for its lead candidate, imdusiran, is highly promising, showing a high rate of functional cure and treatment discontinuation, which could position it as a best-in-class therapy for chronic Hepatitis B. Furthermore, the favorable claim construction ruling in the Pfizer/BioNTech litigation and the upcoming Moderna trial represent substantial potential upside from intellectual property enforcement. While cash reserves have decreased, the improved financial performance and clinical/legal catalysts suggest a strong positive outlook.

Positives

• Maintained a strong financial position with $93.7 million in cash, cash equivalents, and marketable securities.
• Imdusiran clinical data shows significant efficacy: 46% of Phase 2a patients achieved functional cure or discontinued NA therapy, and 94% of long-term follow-up patients remain off treatment for up to 2+ years.
• Imdusiran demonstrated 100% HBV DNA suppression in Phase 1b HBV DNA positive patients by week 18 when combined with NA therapy.
• Received a generally favorable claim construction ruling in the high-stakes Pfizer-BioNTech LNP litigation.
• Achieved a substantial reduction in net loss to $7.7 million in Q3 2025 from $19.7 million in Q3 2024.
• Successfully reduced Research and Development expenses by $8.5 million and General and Administrative expenses through strategic streamlining and cost-cutting.
• Imdusiran has been generally safe and well-tolerated in over 250 patients, with no related serious adverse events (SAEs) or safety-related discontinuations in repeat-dose patients.
• AB-101, an oral PD-L1 inhibitor, demonstrated potent target engagement (up to 100% receptor occupancy at 40mg dose) and a strong safety and tolerability profile in its Phase 1a/1b study.

Negatives

• Cash, cash equivalents, and marketable securities decreased by $28.9 million from $122.6 million at December 31, 2024, to $93.7 million at September 30, 2025.
• Total revenue for Q3 2025 decreased by $0.8 million to $0.5 million, primarily due to a decline in license royalty revenues from Alnylam's ONPATTRO sales.
• Operating activities used $35.0 million during the nine months ended September 30, 2025.
• One functionally cured patient seroreverted, though they remain virally suppressed and off all treatment.

Risks

• Ongoing and anticipated clinical trials may be more costly or take longer to complete than anticipated, may never be initiated or completed, or may not generate results that warrant future development of the tested product candidate.
• The company may elect to change its strategy regarding its product candidates and clinical development activities.
• The company may not receive the necessary regulatory approvals for the clinical development of its product candidates.
• Uncertainties are associated with litigation generally and patent litigation specifically.
• Economic and market conditions may worsen.
• Market shifts may require a change in strategic focus.
• The workforce reduction and plans to reduce net cash burn may not materially extend the cash runway and may create a distraction or uncertainty that could adversely affect operating results, business, or investor perceptions.
• Risks are related to the sufficiency of cash resources for foreseeable and unforeseeable operating expenses and capital expenditures.

Future Outlook

The company remains dedicated to accelerating the development and potential approval of imdusiran. It is evaluating development plans for a Phase 2b clinical trial of imdusiran, including ways to accelerate its development. All remaining restructuring-related payments are expected to be made by the first quarter of 2026. The Moderna U.S. litigation jury trial is scheduled for March 2026, public oral hearings for two Unified Patent Court cases are scheduled for May 2026, and a trial in the Canadian case is set for September 2027.

Management Comments

• "The strength of our third quarter performance reflects our disciplined focus on executing strategic priorities." Lindsay Androski, President and CEO.
• "We are also excited to share additional analysis of imdusiran clinical data being conducted as part of our ongoing strategic review." Lindsay Androski, President and CEO.
• "We remain dedicated to accelerating the development and potential approval of imdusiran." Lindsay Androski, President and CEO.
• "Arbutus continues to consult closely with and support its exclusive licensee, Genevant Sciences, to protect and defend Arbutus' intellectual property."
• "The Company, together with Genevant, is seeking fair compensation for Moderna's and Pfizer/BioNTech's use of Arbutus' patented LNP technology that was developed with great effort and at a great expense, and without which Moderna's and Pfizer/BioNTech's COVID-19 vaccines would not have been successful."

Industry Context

The company operates in the clinical-stage biopharmaceutical sector, specifically targeting chronic Hepatitis B (cHBV) infection, which affects over 250 million people worldwide and represents a significant unmet medical need due to limited non-curative treatment options. The LNP technology litigation against Moderna and Pfizer/BioNTech highlights the critical role of patented drug delivery systems in the development of successful vaccines, particularly in the context of the COVID-19 pandemic. The focus on functional cure for HBV aligns with broader industry efforts to move beyond lifelong suppressive therapies.

Comparison to Industry Standards

• Current nucleos(t)ide analogue (NA) therapy and PEG-IFN treatments for cHBV typically yield low HBsAg seroclearance rates (<1% to 11% at 1-3 years) and functional cure rates (2-7% at 1-8 years). Imdusiran's Phase 2a data, showing 46% of patients achieving functional cure or discontinuing NA therapy and 94% remaining off treatment long-term, suggests a potentially superior efficacy profile.
• Imdusiran's safety profile, with no related serious adverse events (SAEs) or safety-related discontinuations in repeat-dose patients and a low incidence of Grade 1 or 2 ALT elevation (6%), contrasts favorably with PEG-IFN, which has an ~8% discontinuation rate in clinical trials and up to 26% in real-world settings due to tolerability issues.
• Imdusiran's long dosing intervals (4, 8, or 12 weeks) offer improved patient convenience compared to more frequent dosing regimens of some existing therapies.
• The company's LNP technology, central to its patent litigation, is being compared to its use by Moderna and Pfizer/BioNTech in their highly successful COVID-19 vaccines, underscoring its foundational importance in a multi-billion dollar market.

Legal Proceedings

• Ongoing lawsuits against Moderna and Pfizer/BioNTech regarding the use of Arbutus' patented LNP technology in their COVID-19 vaccines.
• Moderna U.S. litigation: Fact discovery, expert discovery, and summary judgment briefing have been completed; a jury trial is scheduled for March 2026.
• Five international lawsuits were filed against Moderna and its affiliates in March 2025, seeking to enforce patents across 30 countries.
• Public oral hearings for two of the five international cases before the Unified Patent Court are scheduled for May 2026.
• A trial in the Canadian case against Moderna is set to begin in September 2027.
• Pfizer/BioNTech litigation: A claim construction hearing occurred in December 2024, and the court issued a generally favorable claim construction ruling in September 2025.

Stakeholder Impact

• Shareholders: Potential for increased value due to positive clinical trial results, favorable litigation outcomes, and improved financial efficiency. Risks include litigation uncertainties and ongoing cash burn.
• Patients (cHBV): Promising new treatment option (imdusiran) with the potential for functional cure and discontinuation of lifelong therapy, offering improved quality of life.
• Employees: Workforce reduction has occurred as part of restructuring efforts, impacting some employees.
• Licensees (Genevant Sciences): Continued support and collaboration in defending intellectual property, with potential for shared benefits from litigation.
• Competitors (Moderna, Pfizer/BioNTech): Direct impact from ongoing patent litigation, potentially leading to significant financial compensation for Arbutus.

Next Steps

• Jury trial for Moderna U.S. litigation scheduled for March 2026.
• Public oral hearings for two Unified Patent Court cases against Moderna scheduled for May 2026.
• Trial in the Canadian case against Moderna set to begin in September 2027.
• Evaluation of development plans for a Phase 2b clinical trial of imdusiran, including ways to accelerate its development.
• Remaining restructuring-related payments expected by Q1 2026.

Key Dates

Recommendation

The company demonstrated strong operational efficiency with a significantly reduced net loss and controlled expenses. The clinical data for imdusiran is highly promising, showing a high rate of functional cure and treatment discontinuation, which could position it as a best-in-class therapy for chronic Hepatitis B. Furthermore, the favorable claim construction ruling in the Pfizer/BioNTech litigation and the upcoming Moderna trial represent substantial potential upside from intellectual property enforcement. While cash reserves have decreased, the improved financial performance and clinical/legal catalysts suggest a strong investment opportunity.

Keywords

Arbutus Biopharma, ABUS, Hepatitis B, cHBV, Imdusiran, AB-729, RNAi therapeutic, LNP technology, Moderna litigation, Pfizer-BioNTech litigation, Patent litigation, Clinical trials, Functional cure, HBV DNA, HBsAg, PD-L1 inhibitor, AB-101, Financial results, Q3 2025, Biopharmaceutical, Drug development, Infectious disease