Vir Biotechnology, Inc. announced that the U.S. Food and Drug Administration (FDA) has cleared its investigational new drug (IND) application and granted Fast Track designation for the combination of tobevibart and elebsiran for the treatment of chronic hepatitis delta infection. Tobevibart, an investigational monoclonal antibody, and elebsiran, an investigational small interfering ribonucleic acid, are currently being evaluated in the Company?s Phase 2 SOLSTICE hepatitis delta clinical trial, with complete 24-week treatment data on track to be reported in the fourth quarter. The FDA?s Fast Track designation is intended to facilitate the development and expedite the review of drugs to treat serious conditions and fill an unmet medical need.

The World Health Organization considers hepatitis delta to be the most severe form of chronic viral hepatitis due to more rapid progression towards liver cancer and liver-related death. It is estimated that at least 12 million people are living with chronic hepatitis delta globally. In June, the Company announced preliminary Phase 2 SOLSTICE trial data which suggests treatment with tobevibart alone or in combination with elebsiran was generally well tolerated and participants achieved high rates of virologic response at weeks 12 and 24, durable virologic response through 48 weeks, and high rates of ALT normalization.

The complete 24-week treatment data is expected in the fourth quarter. The Company is working to expedite the initiation of its next study, the ECLIPSE trial. The open-label, randomized, controlled ECLIPSE trial is designed to support potential registration and will evaluate the safety and efficacy of a monthly-administered subcutaneous injection of tobevibart and elebsiran using the current standard of care therapy as a comparator.

About the Phase 2 SOLSTICE Trial: The SOLSTICE trial (NCT05461170) is evaluating the safety, tolerability and efficacy of tobevibart and elebsiran for the treatment of people living with chronic hepatitis delta. One cohort is evaluating the combination of tobevibart and elebsiran dosed every 4 weeks with a second cohort evaluating tobevibart monotherapy every 2 weeks. Approximately 50% of participants have compensated cirrhosis.

Tobevibart is an investigational subcutaneously administered antibody designed to inhibit entry of hepatitis B and hepatitis delta viruses into hepatocytes, neutralize both hepatitis B virus and hepatitis delta virus virions, and to reduce the level of virions and subviral particles in the blood. Tobevibart, which incorporates Xencor?s Xtend and other Fc technologies, has been engineered to have an extended half-life and was identified using Vir?s proprietary monoclonal antibody discovery platform. Elebsiran is an investigational subcutaneously administered 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.

Vir believes it has the potential to have direct antiviral activity against hepatitis B virus and hepatitis delta virus. It is the first siRNA in the clinic to include Enhanced Stabilization Chemistry Plus (ESC+) technology to enhance stability and minimize off-target activity, which potentially could result in an increased therapeutic index. Elebsiran is the first asset in the Company?s collaboration with Alnylam Pharmaceuticals, Inc. to enter clinical trials.