Vir Biotechnology (Nasdaq: VIR) has announced plans to present significant clinical data from its hepatitis delta and hepatitis B programs at the upcoming European Association for the Study of the Liver (EASL) Congress 2025, taking place in Amsterdam from May 7-10.
The company will showcase results from a 24-week subgroup analysis of its ongoing Phase 2 SOLSTICE trial in chronic hepatitis delta. This analysis examines how baseline viral parameters and cirrhosis status impact virological and biochemical responses in patients treated with the combination of tobevibart and elebsiran. The data has been selected for a poster presentation and will be highlighted during a specialized EASL poster tour on May 8.
Additionally, Vir will present 24-week post-treatment follow-up data from its MARCH Phase 2 clinical study, which evaluates combinations of tobevibart and elebsiran, both alone and in combination with pegylated interferon alfa (PEG-IFNα), in patients with chronic hepatitis B. Professor Edward Gane, Chief Hepatologist at Auckland City Hospital, will deliver this presentation during a general session on May 9.
These new results build upon end-of-treatment data previously presented at the American Association for the Study of Liver Diseases (AASLD) The Liver Meeting® 2024. Those earlier findings demonstrated promising rates of hepatitis B surface antigen (HBsAg) loss, also known as seroclearance, in participants with low baseline HBsAg levels (less than 1000 IU/mL) in both combination treatment regimens.
Innovative Therapeutic Approach
Vir's approach to treating chronic hepatitis B and delta involves a dual mechanism strategy. Tobevibart is a broadly neutralizing monoclonal antibody targeting the hepatitis B surface antigen. It works by inhibiting viral entry into hepatocytes and reducing circulating viral particles in the bloodstream. The antibody incorporates Xencor's Xtend™ technology to extend its half-life and features an engineered Fc domain designed to enhance immune engagement and clearance of HBsAg immune complexes.
Elebsiran, discovered by Alnylam Pharmaceuticals, is a small interfering ribonucleic acid (siRNA) that targets hepatitis B virus. It functions by degrading viral RNA transcripts and limiting the production of hepatitis B surface antigen. Current evidence suggests it may have direct antiviral activity against both hepatitis B and delta viruses.
Both investigational treatments are administered subcutaneously, potentially offering a more convenient administration route compared to some existing therapies.
Clinical Significance
Chronic hepatitis B and delta represent significant global health challenges. Hepatitis delta virus (HDV) is considered the most severe form of viral hepatitis, with limited treatment options currently available. It only occurs as a co-infection with hepatitis B virus (HBV) and can lead to accelerated liver disease progression, including cirrhosis and hepatocellular carcinoma.
Chronic hepatitis B affects approximately 296 million people worldwide, according to the World Health Organization. Despite available treatments, functional cure rates remain low with current standard-of-care therapies.
Dr. Alina Jucov from Arensia Exploratory Medicine GmbH and Nicolae Testemitanu State University of Medicine and Pharmacy will present the SOLSTICE trial data. This study's subgroup analysis is particularly important as it may help identify which patient populations might benefit most from the investigational combination therapy.
The MARCH study's 24-week post-treatment follow-up data will provide crucial insights into the durability of treatment responses after therapy completion. Sustained viral suppression and HBsAg loss after treatment cessation are key indicators of a potential functional cure for chronic hepatitis B.
Additional Research Presentation
Vir will also present in vitro characterization data for elebsiran during a poster session on May 9. Dr. Gregory Camus, Director of Research at Vir Biotechnology, will present this work, which provides deeper insights into the mechanism of action of this investigational siRNA therapeutic targeting hepatitis B virus.
The comprehensive data presentations at EASL 2025 reflect Vir Biotechnology's continued commitment to developing novel therapeutic approaches for patients with chronic viral hepatitis. The company's clinical-stage portfolio extends beyond viral hepatitis to include programs for other infectious diseases and oncology indications.
