By Fineline Cube Brii Biosciences (HKG: 2137) unveiled a cross-study pooled analysis of hepatitis B surface antigen (HBsAg) rebound dynamics following treatment discontinuation in chronic hepatitis B virus (HBV) patients at the 35th Annual Meeting of the Asian Pacific Association for the Study of the Liver (APASL 2026).
The analysis integrated data from two Phase II trials—ENSURE and BRII-179-002—evaluating pegylated interferon alpha (PEG-IFNα) alone or in combination with elebsiran (an HBV-targeting siRNA) or BRII-179 (a therapeutic vaccine). Results demonstrated favorable post-treatment durability: among patients who experienced HBsAg rebound after end of treatment (EOT), all rebound levels remained below 100 IU/mL, with the majority under 10 IU/mL—a threshold associated with reduced long-term complications and improved functional cure prospects.
Therapeutic Assets & Mechanisms
| Agent | Type | Mechanism | Development Status |
|---|---|---|---|
| Elebsiran | Subcutaneously administered siRNA | Silences all HBV RNA transcripts → reduces viral antigens (HBsAg, HBeAg) and DNA; may enhance immune recognition | Phase II (in combo regimens) |
| BRII-179 | Recombinant protein therapeutic vaccine | Stimulates HBV-specific T and B cell responses to restore immune control | Acquired from Vir Biotechnology in 2022; Phase II tested |
Clinical Significance of Low-Level Rebound
- Functional Cure Benchmark: Sustained HBsAg loss or very low levels (<10–100 IU/mL) post-treatment correlate with reduced cirrhosis, hepatocellular carcinoma (HCC), and mortality risk
- Differentiation: Current nucleos(t)ide analogs suppress replication but rarely reduce HBsAg; Brii’s RNAi/vaccine approach targets antigen reduction + immune restoration
- Safety: No severe flares observed during rebound phase, supporting controlled immune reactivation
Strategic Positioning in HBV Cure Landscape
- Combination Strategy: Elebsiran’s direct antiviral effect (lowering antigen load) creates a permissive environment for BRII-179–mediated immune response, mimicking natural clearance
- Global Relevance: Over 290 million people live with chronic HBV; <1% achieve functional cure with current therapies
- Pipeline Synergy: Elebsiran also shows activity against hepatitis D virus (HDV), expanding its therapeutic scope
- Partnership Legacy: BRII-179 originated from Vir Biotechnology, underscoring Brii’s strategy of acquiring and advancing differentiated immuno-virology assets
Next Steps
Brii plans to advance elebsiran-based combinations into Phase III, potentially incorporating newer agents like TLR agonists or checkpoint modulators to further improve cure rates. Regulatory discussions with NMPA and FDA are ongoing.
Forward‑Looking Statements
This brief summarizes early clinical findings. Efficacy, safety, and regulatory pathways remain subject to confirmatory trials and agency feedback.-Fineline Info & Tech