BRII-B (02137) announced the presentation of a cross-study pooled analysis on the characteristics of hepatitis B surface antigen (HBsAg) rebound after treatment cessation at the 35th Annual Meeting of the Asia-Pacific Association for the Study of the Liver (APASL 2026), held from April 22 to 25, 2026, in Istanbul, Turkey.
The analysis evaluated HBsAg rebound occurring after the end of treatment (EOT) in nucleos(t)ide reverse transcriptase inhibitor (NRTI)-experienced participants with chronic hepatitis B virus (HBV) infection who achieved HBsAg clearance in the Phase II ENSURE and BRII-179-002 studies. The ENSURE study is a Phase II trial designed to assess the safety and efficacy of a combination therapy strategy for improving functional cure rates in hepatitis B. Cohorts 1-3 compared the treatment effect of elebsiran combined with pegylated interferon alpha (PEG-IFNα) versus PEG-IFNα monotherapy. Cohort 4 evaluated the potential role of BRII-179 in selecting immunologically responsive populations and increasing HBsAg clearance rates. The BRII-179-002 study is a multicenter, randomized, double-blind, Phase II proof-of-concept trial evaluating a combination regimen of BRII-179 added to a PEG-IFNα backbone.
Data from both studies were pooled to assess the incidence, magnitude, and clinical relevance of HBsAg rebound after EOT in participants treated with PEG-IFNα alone or in combination with either elebsiran or BRII-179. The integrated analysis showed favorable overall clinical outcomes after treatment cessation: rebound HBsAg levels were all below 100 IU/mL, with the majority being below 10 IU/mL. The incidence of HBV DNA rebound after NRTI discontinuation was low, and no clinically significant alanine aminotransferase (ALT) elevations associated with NRTI cessation were observed.
Overall, these results indicate that participants achieved sustained immunological control after treatment ended, further supporting the feasibility of safely discontinuing NRTI in PEG-IFNα-based regimens combined with novel agents. Notably, a shorter NRTI consolidation period (12-20 weeks) did not increase the rate of HBsAg rebound compared to a 24-week NRTI consolidation period, suggesting that shortening or even omitting the NRTI consolidation phase is a viable option in future treatment strategies.
Dr. David Margolis, Chief Medical Officer of the company, stated, "We are encouraged by this accumulating evidence, which indicates that our novel combination regimens can not only achieve rapid HBsAg clearance but also maintain durable immunological control after treatment stops. These findings strengthen our confidence in BRII-179 and elebsiran as key components of next-generation curative strategies for hepatitis B. We look forward to obtaining further data from ongoing studies throughout 2026."