- Final results from the ENSURE study show that the combination of pegylated interferon alpha (PEG‑IFNα) with elebsiran achieves higher functional cure rates compared to PEG‑IFNα alone
- Data from Cohort 4 indicate that participants who previously responded to BRII‑179 treatment achieved the most significant functional cure outcomes, further supporting its potential clinical benefit
- Data from an ENSURE translational study suggest that BRII‑179-induced epitope-mismatched CD4+ T cells and their promotion of HBs-specific B cell maturation are associated with increased HBsAg clearance rates following curative therapy, providing new insights into its potential mechanism of action
Beijing, China and Durham, North Carolina, USAMay 27, 2026 /PRNewswire/ — Brii Biosciences Limited (“Brii Biosciences” or the “Company”, Stock Code: 2137.HK), a biotechnology company dedicated to developing therapies for diseases with significant unmet patient needs to improve patient health and treatment options, today announced the final results from Cohorts 1-4 of its Phase 2 ENSURE study at the European Association for the Study of the Liver (EASL) 2026 Congress in Barcelona, Spain.
All participants who completed treatment with PEG‑IFNα combined with elebsiran subsequently received a 24-week consolidation therapy with nucleos(t)ide analogues (NA). This release presents the functional cure rates at the end of the ENSURE study, defined as sustained HBsAg clearance with undetectable HBV DNA for at least 24 weeks after cessation of all treatments, including NA. Final results show that the HBsAg clearance benefit observed in the elebsiran plus PEG‑IFNα treatment cohorts translated into higher functional cure rates compared to PEG‑IFNα monotherapy. Participants who previously received BRII‑179 treatment, particularly anti‑HBs responders, achieved higher functional cure rates, suggesting that BRII‑179 may play an important role in achieving durable immunological control of HBV.
Brii Biosciences is conducting two additional Phase 2b clinical studies to further clarify the role of BRII‑179 in the treatment of chronic hepatitis B and to optimize combination regimens for pivotal studies. Among these, the ENRICH study aims to evaluate the role of BRII‑179 in activating HBV-specific immune responses and to identify immune responder populations more likely to achieve functional cure. The ENHANCE study includes two parts: one evaluating a 48-week concurrent triple combination regimen of BRII‑179, elebsiran, and PEG‑IFNα; the other evaluating a sequential regimen with an initial 24-week treatment of BRII‑179 combined with elebsiran, followed by a 24-week triple combination therapy. End-of-treatment (EOT) data from both studies are expected to be released in 2026.
Dr. David Margolis, Chief Medical Officer of Brii Biosciences, stated: “We are encouraged by the consistent findings observed in the ENSURE study and believe these final results highlight the potential of BRII‑179 and elebsiran to enhance functional cure outcomes. The ENSURE results, combined with data from our upcoming ongoing trials, will provide key insights to inform the future development plan for our HBV functional cure program.”
Details of the late-breaker poster presentation are as follows:
Title: Functional Cure Rates in Participants with Chronic Hepatitis B Virus Infection Treated with Elebsiran Combined with Pegylated Interferon Alpha: Final Results from the ENSURE Phase 2 Study
Session/Presentation Format: Late-Breaker Poster
Presentation Date and Time: May 27, 8:30 to May 30, 16:00 (UTC+2)
Abstract Number: LB26‑5012 / LBP‑040
Presenter: Professor Grace L.H. Wong, MBChB (CUHK), MD (CUHK), FRCP (Lond, Edin), FHKCP, FHKAM (Medicine), Professor of Gastroenterology and Hepatology, Medical Data Analytics Centre (MDAC) and Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, China
- At Week 72 (24 weeks post-end of treatment EOT), 19 of the 20 participants who achieved HBsAg clearance met NA discontinuation criteria and entered an additional 24-week follow-up period; the remaining participant was still HBeAg positive.
- In Cohorts 1-3, functional cure rates in the elebsiran 200 mg or 100 mg plus PEG‑IFNα treatment cohorts were 2/19 (10.5%) and 3/18 (16.7%), respectively, higher than the 1/18 (5.6%) in the PEG‑IFNα monotherapy cohort. In Cohort 4, 8/31 (25.8%) participants achieved functional cure, with anti‑HBs responders at 7/19 (36.8%), significantly higher than non-responders at 1/12 (8.3%).
- No new treatment-related adverse events (TRAEs) were reported after NA discontinuation, and most TRAEs resolved during the post-EOT follow-up period.
- Participants who achieved sustained HBsAg clearance through combination therapy showed favorable clinical outcomes after NA discontinuation, including a low rate of HBV DNA rebound and no observed alanine aminotransferase (ALT) elevations.
In another oral presentation, Dr. Nina Le Bert will report results from a translational study using samples from ENSURE and the prior BRII-179-835-001 trial to evaluate immune responses associated with BRII-179. The study identified a novel mechanism: BRII-179 induces CD4+ T cell responses targeting epitope sequences in the Pre-S1 region that are mismatched with circulating hepatitis B virus (HBV) genotypes. These vaccine-induced T cells remained functionally stable for over two years and persisted during subsequent PEG-IFNα and siRNA treatment. Notably, these T cell responses were associated with progressive maturation of HBs-specific B cells during treatment, an effect linked to improved HBsAg clearance rates. These findings provide new insights into the potential mechanism underlying BRII-179-mediated functional cure.
For more information on Brii Biosciences’ HBV drug candidates, please visit: www.briibio.com.
About Hepatitis B
Hepatitis B virus (HBV) infection is one of the most significant infectious disease threats worldwide, with over 254 million people infected globally.[1] Chronic HBV infection is a leading cause of liver disease, resulting in approximately 820,000 deaths annually from complications of chronic HBV infection.1 In China, chronic HBV infection affects 87 million people, a matter of significant concern.[2]
About BRII-179
BRII-179 is a novel recombinant protein-based HBV immunotherapeutic candidate that expresses HBV Pre-S1, Pre-S2, and S surface antigens, designed to induce enhanced and broad B cell and T cell immune responses. In November 2023, the Center for Drug Evaluation (CDE) of China’s National Medical Products Administration (NMPA) granted BRII-179 Breakthrough Therapy designation.
About Elebsiran
Elebsiran is an investigational subcutaneously administered small interfering ribonucleic acid (siRNA) targeting hepatitis B virus (HBV), designed to degrade HBV RNA transcripts and limit the production of hepatitis B surface antigen, with direct antiviral activity against HBV and hepatitis delta virus (HDV). It is the first siRNA to enter clinical development using enhanced stabilization chemistry to increase stability and minimize off-target activity, potentially improving the therapeutic index. Brii Biosciences obtained exclusive rights from Vir Biotechnology, Inc. in 2020 to develop and commercialize elebsiran in Greater China. In May 2024, the CDE of China’s NMPA granted elebsiran Breakthrough Therapy designation.
About Brii Biosciences
Brii Biosciences (Stock Code: 2137.HK) is a biotechnology company dedicated to developing therapies for areas with significant unmet patient needs and limited treatment options to improve patient health. The Company is advancing a unique pipeline of drug candidates, including its most advanced program targeting hepatitis B virus (HBV) infection. Led by a visionary and experienced leadership team, the Company operates in both China and the United States. For more information, please visit www.briibio.com.
[2] World Health Organization. Hepatitis. World Health Organization. Retrieved from https://www.who.int/china/health-topics/hepatitis#:~:text=There%20are%2087%20million%20people,living%20with%20chronic%20hepatitis%20C.