Vir Biotechnology announced positive end-of-treatment results from Part B of the MARCH Phase 2 clinical study, evaluating combinations of tobevibart and elebsiran for chronic hepatitis B treatment. The study demonstrated promising rates of hepatitis B surface antigen (HBsAg) loss, with 39% of participants achieving HBsAg loss with the doublet regimen (tobevibart and elebsiran) and 46% with the triplet regimen (tobevibart, elebsiran, and pegylated interferon alfa) in patients with low baseline HBsAg levels (<1000 IU/mL). These findings were presented at the American Association for the Study of Liver Diseases (AASLD) The Liver Meeting.
Key Efficacy and Safety Findings
The MARCH study included patients with chronic hepatitis B, a condition affecting an estimated 254 million people worldwide, according to the World Health Organization. Current treatments often require lifelong administration and do not always prevent disease progression to cirrhosis, liver failure, or liver cancer. The trial aimed to assess whether a finite treatment regimen could achieve a functional cure, defined as sustained off-treatment HBsAg loss.
The data revealed that in patients with low baseline HBsAg, 39% achieved HBsAg loss with the doublet regimen, while 46% achieved HBsAg loss with the triplet regimen. Notably, all participants who achieved HBsAg loss in the triplet arm also experienced anti-HBs seroconversion (100%, 6/6), indicating the development of antibodies against the hepatitis B virus. The safety profile of both regimens was consistent with prior studies, with treatment-emergent adverse events generally reported as mild to moderate.
Implications for Hepatitis B Treatment
Edward J. Gane, M.D., Professor of Medicine at the University of Auckland, commented on the results, stating, "These latest data at end of treatment are encouraging as they suggest that tobevibart in combination with elebsiran could be key components for a hepatitis B functional cure." He also expressed anticipation for further results expected next year.
Mark Eisner, M.D., M.P.H., Executive Vice President and Chief Medical Officer at Vir Biotechnology, added, "The MARCH data suggests that tobevibart and elebsiran can clear HBsAg and re-ignite the immune system, producing antibodies to potentially keep the virus under control."
Study Design and Future Directions
The MARCH study is a Phase 2, multi-center, open-label, non-randomized trial evaluating the safety, tolerability, and efficacy of tobevibart and elebsiran, alone or in combination with pegylated interferon alfa, in patients with chronic hepatitis B. The primary endpoints included HBsAg seroclearance and treatment-emergent adverse events at the end of treatment. Secondary endpoints included anti-HBs seroconversion.
Vir Biotechnology anticipates releasing key functional cure data from the 24-week follow-up in Q2 2025, which will be crucial for determining the long-term effectiveness and commercial viability of the treatment regimens. The company is targeting an unmet medical need, as current treatments require lifelong administration and do not prevent disease progression. A functional cure would represent a significant advancement in the treatment of chronic hepatitis B.
