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4w ago

New Hepatitis B Drug Produces Functional Cure in About One in Five Patients

Regulators in the US, Europe, Japan and China are fast-tracking reviews after phase 3 results that could shorten or stop lifelong antiviral therapy for a subgroup of patients.

© studiovin via Shutterstock
Signage is pictured in the main lobby of GSK offices in London, Britain, February 20, 2025. REUTERS/Chris J. Ratcliffe/File Photo
This 1981 electron microscope image made available by the U.S. Centers for Disease Control and Prevention shows hepatitis B virus particles, indicated in orange. The round virions, which measure 42nm in diameter, are known as Dane particles. Nov. 3, 2021, a government advisory committee recommended that all U.S. adults younger than 60 be vaccinated against hepatitis B, because progress against the liver-damaging disease had stalled. New research in 2026 suggests a "functional cure" may be attainable. (Dr. Erskine Palmer/CDC via AP)

Overview

  • The phase 3 B-Well 1 and B-Well 2 trials, reported May 28, enrolled about 1,838 adults and found bepirovirsen produced functional cure rates of 20% and 19% in the two studies versus 0% with placebo.
  • A functional cure was defined by the trials as undetectable HBV DNA plus loss of hepatitis B surface antigen (HBsAg) sustained for at least 24 weeks, which permitted stopping standard nucleoside/nucleotide analogue (NA) therapy.
  • Treatment was linked to more adverse events than placebo, including transient ALT enzyme elevations in roughly 24% of bepirovirsen recipients that were strongly associated with response—patients with these ALT rises had about an 85% chance of HBsAg loss.
  • The trials enrolled patients on stable NA therapy with baseline HBsAg ≤3,000 IU/mL and excluded people with cirrhosis or certain coinfections, with higher cure rates (≈25–28%) seen in those with HBsAg ≤1,000 IU/mL and much lower rates at higher antigen levels.
  • Bepirovirsen is under expedited review in multiple markets with a U.S. decision expected in October 2026, GSK is preparing launches and partnerships, and experts say longer follow-up and broader trials are needed to confirm durability and wider safety in real-world patients.