Vir Biotechnology Initiates Second Pivotal Trial for Chronic Hepatitis Delta Treatment

Vir Biotechnology has initiated the ECLIPSE 2 Phase 3 clinical trial for chronic hepatitis delta, assessing the efficacy of tobevibart and elebsiran in patients unresponsive to bulevirtide. This trial is part of a global registrational program aiming to secure regulatory approval for these treatments in the US and Europe. The program aims to provide necessary efficacy and safety data to address the urgent need for effective therapies for chronic hepatitis delta, which can lead to liver cancer, cirrhosis, and liver-related mortality.

Vir Biotechnology, Inc. (Nasdaq: VIR) has announced the enrollment of the first participant in the ECLIPSE 2 Phase 3 clinical trial, designed to evaluate the efficacy of the combination of tobevibart and elebsiran in patients with chronic hepatitis delta (CHD) who have not achieved undetectable hepatitis delta virus (HDV) RNA despite bulevirtide treatment. This trial is part of the global registrational ECLIPSE program, which aims to secure regulatory approval for these treatments in the U.S. and Europe.

The ECLIPSE 2 trial is one of three pivotal studies in the ECLIPSE registrational program, which was initiated in March 2025. The program is designed to provide the necessary efficacy and safety data for potential submission to global regulatory agencies. ECLIPSE 2 will enroll participants in regions where bulevirtide is approved for CHD, with the primary endpoint measuring HDV RNA at the lower limit of quantification target not detected (HDV RNA TND) at Week 24.

CHD is the most severe form of chronic viral hepatitis, with people living with the disease rapidly progressing to cirrhosis, liver failure, and liver-related death. There are currently no approved treatments in the U.S., and options are limited in the European Union and globally. The objective of therapy is to eliminate the virus, and tobevibart in combination with elebsiran offers the potential to achieve this by tackling the viral lifecycle through multiple mechanisms.

The significant unmet need in CHD has been recognized by the U.S. Food and Drug Administration (FDA) with Breakthrough Therapy and Fast Track designations, and by the European Medicines Agency (EMA) with Priority Medicines (PRIME) and orphan drug designations.

The ECLIPSE registrational program includes three randomized, controlled trials designed to evaluate the combination therapy in comparison to deferred treatment or bulevirtide. ECLIPSE 1 is currently recruiting and will evaluate the safety and efficacy of tobevibart in combination with elebsiran compared to deferred treatment in the U.S. or other regions where bulevirtide use is limited. ECLIPSE 3 is a Phase 2b head-to-head trial to evaluate tobevibart and elebsiran compared with bulevirtide in bulevirtide-naïve patients.

Tobevibart is an investigational broadly neutralizing monoclonal antibody targeting the hepatitis B surface antigen (HBsAg), designed to inhibit the entry of hepatitis B and hepatitis delta viruses into hepatocytes and to reduce the level of circulating viral and subviral particles in the blood. Elebsiran is an investigational hepatitis B virus-targeting small interfering ribonucleic acid (siRNA) discovered by Alnylam Pharmaceuticals, Inc., designed to degrade hepatitis B virus RNA transcripts and limit the production of hepatitis B surface antigen.

The trial results will be closely watched by investors and financial professionals, as they could significantly impact Vir Biotechnology's clinical development plans and potential regulatory approvals. The successful completion of the ECLIPSE program could lead to the development of a highly effective treatment for people living with chronic hepatitis delta, addressing a critical unmet medical need.

References:
[1] https://www.morningstar.com/news/business-wire/20250731294819/vir-biotechnology-initiates-second-pivotal-trial-in-its-global-eclipse-registrational-program-for-chronic-hepatitis-delta