Bepirovirsen (HIBSAGO) approved in Japan as first functional cure for chronic Hepatitis B. Approval in EU expected in the first half of 2027

GSK announced that Hibsago (bepirovirsen) has been approved by Japan’s MHLW as a functional cure (FC) for CHB patients who have received ≥6 months of nucleos(t)ide analog (NA) therapy, and who, at treatment initiation, have baseline levels of HBsAg ≤ 3000 IU/mL and HBV DNA < 90 IU/mL.

Key Highlights: (Press Release, link to Japanese Package Insert)

• The approval in Japan is the first global approval for bepirovirsen, the first and only approved CHB functional cure.
  • Approval was supported by Phase 3 B-Well data demonstrating that 6-month treatment with bepirovirsen achieved statistically significant FC rates of 19% in patients with baseline HBsAg ≤3,000 IU/mL and 26% in patients with baseline HBsAg ≤1,000 IU/mL.
• From the Japanese Package Insert:
  • Section 6. Dosage and Administration – Specifically notes that “HIBSAGO must always be used in combination with an NA”
  • Section 7.3. Early treatment response – Notes “Consider discontinuing HIBSAGO if an early treatment response is not achieved”.  Section 17 (Clinical Studies) provides further detail from the pooled Ph 3 analysis, noting that patients who achieved an early treatment response (as determined by HBsAg at Wk 12) had a higher FC rate vs those who did not
  • Section 7.4 NA discontinuation – Provides guidance on how long to continue NA (through Wk 48), and in what patients NA discontinuation may be considered – HbeAg-negative, HBV DNA < LLOQ, undetectable HBsAg (<0.05 IU/ml), ALT <2X ULN. Further information in Section 17 (Clinical Studies)
  • Section 8 Important Precautions – Guidance for quantitative HBsAg testing to assess response, liver monitoring, platelet monitoring, renal monitoring
  • Section 17 Clinical Studies - Functional cure rates from Ph 3 studies are separated by subpopulation, showing that FC rates were higher in the HBsAg ≤1000 IU/ml subgroup as compared to the >1000-≤3000 IU/ml subgroup

• Regulatory timelines: Japan’s MHLW accepted GSK’s NDA for bepirovirsen in Feb 2026, marking its first global regulatory filing, with approval following ~6 months later under the expedited SENKU pathway. GSK is also awaiting regulatory decisions in other geographies including:
  • US: Accepted for priority regulatory review by the FDA in April 2026; Breakthrough Therapy Designation, PDUFA date set for Oct 26, 2026
  • China: Accepted for priority regulatory review by the NMPA in Mar 2026; Breakthrough Therapy Designation (decision anticipated 1H’2027)
  • EU: Accepted for regulatory review by the EMA in Mar 2026 (decision anticipated 1H’2027)
  • Canada: Accepted for priority regulatory review by Health Canda in April 2026