8-K: Arbutus Presents Key Hepatitis B Data at AASLD 2025

Arbutus Biopharma announced the acceptance of four abstracts, including a 'Poster of Distinction' for AB-101, for presentation at The Liver Meeting 2025.

Summary

• Arbutus Biopharma will present four abstracts at The Liver Meeting 2025, American Association for the Study of Liver Diseases (AASLD), from November 7-11, 2025, in Washington, DC.
• Three abstracts feature clinical data for imdusiran (AB-729), an RNAi therapeutic for chronic hepatitis B virus (cHBV).
• One abstract features clinical data for AB-101, an oral PD-L1 inhibitor, which has been selected as a 'Poster of Distinction'.
• Imdusiran was found safe and well-tolerated in cHBV patients at 60 mg and 90 mg doses every 8 weeks for 24-48 weeks, with up to 48 weeks of follow-up.
• Preliminary data suggest imdusiran may enhance pegylated interferon alfa-2a responsiveness in cHBV patients with specific HBV genotypes (B or C).
• Imdusiran treatment is associated with increases in soluble immune biomarkers, with greater breadth and magnitude observed in subjects who achieved HBsAg loss.
• AB-101 oral doses up to 30 mg QD for 28 days were generally well tolerated in NA-suppressed cHBV patients, showing dose-related increases in PD-L1 receptor occupancy (83% mean maximal at 30 mg dose).

Sentiment

Score: 7

Explanation: The announcement is positive, highlighting progress in clinical development and validation through abstract acceptance at a major conference, including a 'Poster of Distinction.' However, it's an update on ongoing research, not a definitive clinical trial readout or commercial milestone, and some findings require further study.

Positives

• Acceptance of four abstracts for presentation at a prestigious medical conference (AASLD The Liver Meeting 2025) validates ongoing research.
• AB-101 abstract selected as a 'Poster of Distinction,' highlighting its significance and potential.
• Imdusiran (AB-729) demonstrated safety and good tolerability in chronic hepatitis B patients at both 60 mg and 90 mg dose levels over extended periods.
• Preliminary findings suggest imdusiran may enhance the responsiveness of pegylated interferon alfa-2a in cHBV patients with specific genotypes (B or C), which could improve treatment outcomes.
• Imdusiran treatment is associated with positive changes in soluble immune biomarkers, indicating a potential reawakening of the immune system.
• AB-101 showed general tolerability and dose-related increases in PD-L1 receptor occupancy, supporting its mechanism of action as an oral PD-L1 inhibitor.
• Eight patients have achieved a functional cure for cHBV following treatment with imdusiran and NA therapy in combination with either IFN or low-dose nivolumab plus an immunotherapeutic.

Negatives

• The finding regarding imdusiran enhancing IFN responsiveness is based on a 'limited dataset' and 'further studies in larger cohorts are warranted to confirm these observations'.

Risks

• Ongoing and anticipated clinical trials may be more costly or take longer to complete than expected.
• Clinical trials may never be initiated or completed, or may not generate results that warrant future development of the tested product candidate.
• Arbutus may elect to change its strategy regarding its product candidates and clinical development activities.
• Arbutus may not receive the necessary regulatory approvals for the clinical development of its product candidates.
• Economic and market conditions may worsen.
• Market shifts may require a change in strategic focus.

Future Outlook

Arbutus anticipates that its product candidates, imdusiran and AB-101, have the potential to lead to a functional cure for chronic hepatitis B virus (HBV). The company expects its clinical trials to be effective and timely, generating useful data, and foresees continued demand for its assets under stable economic and market conditions. Arbutus plans to continue its pipeline and development efforts for its cHBV programs.

Management Comments

• Multiple abstracts accepted featuring imdusiran clinical data highlighting progress toward a potential functional cure for chronic hepatitis B virus.
• AB-101 clinical data abstract recognized as a Poster of Distinction.

Industry Context

The acceptance of these abstracts at AASLD's The Liver Meeting 2025, a premier conference for liver disease, positions Arbutus Biopharma at the forefront of chronic Hepatitis B (cHBV) research. The focus on RNAi therapeutics (imdusiran) and PD-L1 inhibitors (AB-101) reflects current industry trends towards developing novel mechanisms for achieving a functional cure for cHBV, a disease with a significant global unmet medical need affecting over 250 million people worldwide. The 'Poster of Distinction' for AB-101 further highlights the potential innovation in checkpoint blockade for infectious diseases, aiming to overcome systemic safety issues seen with antibody therapies.

Comparison to Industry Standards

• The preliminary findings suggesting imdusiran may enhance pegylated interferon alfa-2a responsiveness in cHBV patients with specific HBV genotypes (B or C) 'contrast with historical data from IFN therapy,' indicating a potential improvement over existing standard treatments.
• AB-101, as an oral PD-L1 inhibitor, is designed to allow for controlled checkpoint blockade while minimizing the systemic safety issues typically seen with checkpoint antibody therapies, positioning it as a potentially safer alternative to current immunotherapeutic approaches.
• The achievement of a functional cure in eight patients with imdusiran and NA therapy in combination with either IFN or low-dose nivolumab plus an immunotherapeutic demonstrates progress towards a challenging therapeutic goal, aligning with the industry's pursuit of functional cures for cHBV.

Legal Proceedings

• Ongoing lawsuits against Moderna and Pfizer/BioNTech for use of Arbutus's patented LNP technology in their COVID-19 vaccines.

Stakeholder Impact

• Shareholders: Positive news regarding clinical progress and validation at a major conference could instill confidence, but the early-stage nature of some findings and ongoing IP litigation introduce uncertainty.
• Patients with cHBV: Continued progress in developing imdusiran and AB-101 offers hope for improved treatment options and a potential functional cure for chronic hepatitis B.
• Medical Community/Researchers: The presentation of data at AASLD contributes to the scientific understanding of cHBV treatment and potential new therapeutic approaches.
• Employees: Positive clinical updates can boost morale and reinforce the company's mission.

Next Steps

• Presentation of imdusiran and AB-101 data at AASLD The Liver Meeting 2025 (November 7-11, 2025).
• Further studies in larger cohorts are warranted to confirm observations regarding imdusiran's enhancement of IFN responsiveness.
• Cohort 3B for AB-101 is ongoing, with all available data (safety, PK, receptor occupancy, HBV biomarkers) to be presented.
• Continued development of imdusiran (AB-729) and AB-101 for the treatment of cHBV infection.
• Consulting closely with and supporting Genevant Sciences to protect and defend intellectual property, including ongoing lawsuits against Moderna and Pfizer/BioNTech.

Key Dates

Recommendation

While the acceptance of abstracts at a major conference, especially the 'Poster of Distinction' for AB-101, is a positive validation of Arbutus's clinical programs, these are still early-stage clinical data presentations, not definitive trial readouts. The findings for imdusiran's enhanced IFN responsiveness require further study in larger cohorts. The company also faces ongoing intellectual property litigation, which introduces a significant element of uncertainty. Given the early stage of development and existing legal overhang, a 'hold' recommendation is appropriate, awaiting more substantial clinical milestones or resolution of the IP disputes before a stronger stance can be taken.

Keywords

Arbutus Biopharma, ABUS, Hepatitis B, cHBV, Imdusiran, AB-729, AB-101, AASLD, The Liver Meeting 2025, RNAi therapeutic, PD-L1 inhibitor, Clinical Trials, Biopharma, Infectious Disease, Liver Disease, Functional Cure