DURHAM, North Carolina & BEIJING, China, July 3, 2026
Brii Biosciences Limited (Brii Bio) has announced positive topline end-of-treatment (EOT) results from its ongoing Phase 2b ENRICH and ENHANCE clinical studies, highlighting significant progress toward developing a functional cure for chronic hepatitis B (HBV). The studies evaluated sequential and concurrent combination regimens involving BRII-179, elebsiran, and PEG-IFNα in patients with chronic HBV infection. The latest findings demonstrated that the ENRICH sequential treatment strategy achieved substantially higher hepatitis B surface antigen (HBsAg) loss rates, confirming the immune-priming role of BRII-179 and supporting its advancement as the preferred regimen for future registrational development. The results strengthen Brii Bio’s position in the rapidly evolving HBV therapeutic landscape, where achieving sustained HBsAg loss remains one of the most important milestones toward a functional cure. While the company has reached preliminary regulatory alignment with China’s National Medical Products Administration (NMPA) regarding a potential Phase 3 program, further clinical advancement remains dependent on the resolution of an ongoing arbitration involving elebsiran manufacturing technology.
ENRICH Study Confirms BRII-179 Immune Priming Improves Functional Cure Potential
The ENRICH Phase 2b study was designed to evaluate BRII-179 as an immune-priming therapy administered before treatment with elebsiran and pegylated interferon alpha (PEG-IFNα). End-of-treatment data demonstrated HBsAg loss rates of 42.9% (42/98) in patients receiving five doses of BRII-179 every three weeks and 40.0% (20/50) in those receiving seven doses every two weeks. These findings were highly consistent with the previously reported 41.9% HBsAg loss rate observed in ENSURE Cohort 4, providing compelling evidence that BRII-179 effectively enhances immune responses before antiviral therapy. Subgroup analyses also suggested encouraging efficacy among patients with higher baseline HBsAg levels (1000–3000 IU/mL), reinforcing previous observations that immune priming may benefit patients traditionally considered difficult to treat.
Based on these encouraging results, Brii Bio confirmed that it has engaged with the Center for Drug Evaluation (CDE) of China’s National Medical Products Administration (NMPA) and achieved preliminary alignment regarding the design of a potential registrational Phase 3 clinical study, bringing the company one step closer to developing a next-generation functional cure strategy for chronic hepatitis B.
ENHANCE Findings Guide Future HBV Combination Therapy Development
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The companion ENHANCE Phase 2b study evaluated a concurrent triple-combination regimen of BRII-179, elebsiran, and PEG-IFNα to determine whether simultaneous administration could further improve functional cure rates. At end of treatment, the study reported an HBsAg loss rate of 25.5% (25/98), which did not exceed the 29.7% previously observed in ENSURE Cohorts 2 and 3. However, the regimen still demonstrated meaningful clinical activity compared with the PEG-IFNα control arm, which achieved an HBsAg loss rate of only 10.2% (5/49). ENHANCE Part A-2 also evaluated an alternative sequential regimen intended to shorten PEG-IFNα exposure by administering BRII-179 plus elebsiran before introducing PEG-IFNα.
This approach achieved an HBsAg loss rate of 22.5% (18/80), indicating that a full course of PEG-IFNα therapy remains important for maximizing treatment outcomes. Importantly, no new safety concerns were identified across either study, supporting the favorable safety profile of the investigational combination regimens. Brii Bio plans to present additional efficacy, safety, subgroup analyses, and durability data during a scientific conference later in 2026.
Phase 3 Development Depends on Resolution of Vir Biotechnology Arbitration
Despite the encouraging clinical outcomes, Brii Bio emphasized that advancement of the ENRICH program into Phase 3 remains contingent upon the outcome of its ongoing arbitration with Vir Biotechnology regarding elebsiran manufacturing technology transfer. The company stated that it cannot initiate a registrational Phase 3 study involving elebsiran-containing combination therapies until the arbitration is satisfactorily resolved. According to Chief Medical Officer Dr. David Margolis, the consistency of results observed across ENRICH, ENHANCE, and earlier ENSURE studies strongly supports the ENRICH sequential treatment design as the preferred pathway for future registration.
BRII-179, a recombinant protein-based HBV immunotherapeutic, and elebsiran, an investigational siRNA therapy, have both received Breakthrough Therapy Designation from China’s NMPA, underscoring their potential to address one of the world’s largest unmet medical needs. With more than 254 million people living with chronic hepatitis B worldwide, Brii Bio’s latest Phase 2b data represent an important step toward delivering innovative functional cure therapies capable of transforming long-term HBV management and improving outcomes for millions of patients globally.
Source: Brii Bio press release
