Vir Biotechnology has received a positive opinion from the European Medicines Agency (EMA) Committee for Orphan Medicinal Products (COMP) for its application for orphan drug designation for tobevibart and elebsiran in the treatment of chronic hepatitis delta (CHD). The decision follows encouraging preliminary data from the Phase 2 SOLSTICE trial, which were presented at The Liver Meeting of the American Association for the Study of Liver Diseases (AASLD). This designation underscores the potential of tobevibart and elebsiran to address a critical unmet need in the treatment of CHD, a severe and progressive liver disease.
Addressing a Critical Unmet Need in CHD
Chronic hepatitis delta is caused by the hepatitis delta virus (HDV) and is considered the most aggressive form of chronic viral hepatitis. Patients with CHD often progress to cirrhosis and liver failure within five years of infection. According to Mark Eisner, M.D., M.P.H., Executive Vice President and Chief Medical Officer at Vir Biotechnology, new therapeutic options are urgently needed, as CHD dramatically raises the risk of severe liver disease, including cancer, and death.
Currently, there is no approved treatment for CHD in the United States, and treatment options are limited in the European Union and globally. The positive opinion on tobevibart and elebsiran reflects the potential of this combination to address a critical gap in hepatitis delta care, with clinical data suggesting that this approach could meaningfully improve outcomes for patients living with this devastating disease.
Orphan Drug Designation: Incentives and Benefits
The European Commission will evaluate the COMP’s positive opinion and consider tobevibart and elebsiran for orphan drug designation. This designation is reserved for medicines intended to treat rare, life-threatening, or chronically debilitating conditions where no other satisfactory treatment option is available, or where the medicine can be of significant benefit to those affected by a specific condition. Orphan drug designation provides special incentives in the EU, including access to specific scientific advice, fee reductions, and 10 years of market exclusivity once the medicine is approved.
SOLSTICE Trial and Clinical Development
The Phase 2 SOLSTICE trial is a multi-center, open-label, randomized study evaluating the safety, tolerability, and efficacy of tobevibart, alone or in combination with elebsiran, in patients with chronic hepatitis delta. Primary endpoints include the proportion of participants with undetectable hepatitis delta virus (HDV) RNA and alanine aminotransferase (ALT) normalization up to week 24, as well as treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs) up to 118 weeks. Secondary endpoints include the proportion of participants with undetectable HDV RNA at different time points and up to 192 weeks.
Tobevibart and Elebsiran: Novel Therapeutic Approaches
Tobevibart is an investigational, broadly neutralizing monoclonal antibody targeting the hepatitis B surface antigen. It is 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. Tobevibart incorporates Xencor’s Xtend™ and other Fc technologies, engineered for an extended half-life. It is administered subcutaneously and is currently in clinical development for treating patients with chronic hepatitis B and chronic hepatitis delta.
Elebsiran is an investigational, hepatitis B virus-targeting small interfering ribonucleic acid (siRNA) designed to degrade hepatitis B virus RNA transcripts and limit the production of hepatitis B surface antigen. Current data indicates that it has the potential to have direct antiviral activity against hepatitis B virus and hepatitis delta virus. Elebsiran is administered subcutaneously and is currently in clinical development for treating patients with chronic hepatitis B and chronic hepatitis delta. It is the first asset in Vir Biotechnology’s collaboration with Alnylam Pharmaceuticals, Inc. to enter clinical studies.
FDA Fast Track Designation
In June 2024, the U.S. Food and Drug Administration (FDA) granted fast track designation for the combination of tobevibart and elebsiran for the treatment of CHD. This designation is intended to facilitate the development and expedite the review of drugs to treat serious conditions and fill an unmet medical need.
