Vir Biotechnology, Inc. (NASDAQ: VIR) has announced end-of-treatment data from Part B of its MARCH Phase 2 study, evaluating combinations of tobevibart and elebsiran, with or without pegylated interferon alfa (PEG-IFNα), in participants with chronic hepatitis B (CHB). The study demonstrated promising rates of hepatitis B surface antigen (HBsAg) loss (seroclearance), particularly in participants with low baseline HBsAg levels (<1000 IU/mL). These results offer hope for improved treatment outcomes for the millions affected by this chronic liver disease.
MARCH Phase 2 Study Details
The MARCH Phase 2 trial investigated the efficacy of tobevibart and elebsiran, administered either alone (doublet regimen) or in combination with PEG-IFNα (triplet regimen). The primary focus was on achieving HBsAg loss, a key indicator of viral control and potential functional cure.
Key Findings on HBsAg Loss
The study revealed that the doublet regimen resulted in HBsAg loss at the end of treatment in 39% (7/18) of participants with baseline HBsAg <1,000 IU/mL. The triplet regimen showed even greater efficacy, with HBsAg loss in 46% (5/11) of participants with similar baseline HBsAg levels. Overall, the proportion of participants achieving HBsAg loss at the end of treatment was 16% (8/51) for the doublet and 22% (6/27) for the triplet regimen across varying baseline HBsAg levels.
Anti-HBs Seroconversion
An important aspect of the study was the assessment of anti-HBs seroconversion, which indicates the development of antibodies against the hepatitis B virus. The doublet regimen led to 50% (4/8) of participants achieving both HBsAg loss and anti-HBs seroconversion. Notably, all participants who experienced HBsAg loss in the triplet regimen also achieved anti-HBs seroconversion (100%, 6/6).
Next Steps and Functional Cure Assessment
Participants who achieved HBsAg seroclearance at the end of treatment and meet specific eligibility criteria will discontinue treatment. A functional cure assessment will be conducted 24 weeks after treatment discontinuation to evaluate the durability of the response.
Expert Commentary
Mark Eisner, Executive Vice President and Chief Medical Officer at Vir Biotechnology, expressed optimism regarding the results. "We are encouraged by these results and eagerly anticipate the functional cure data in 2025, as it will be decisive for the next steps of clinical development," he stated.
Chronic Hepatitis B: A Global Health Challenge
Chronic hepatitis B (CHB) is a persistent inflammatory liver disease caused by the hepatitis B virus (HBV). The World Health Organization estimates that 254 million people live with CHB, contributing to an estimated 1.1 million deaths annually. The development of effective treatments is crucial to addressing this significant global health burden.
