The US Food and Drug Administration has approved Hibsago, the first drug to offer what doctors call a “functional cure” for chronic hepatitis B — suppressing the virus to undetectable levels, with control persisting even after treatment stops.
Key Points
- FDA approves Hibsago hepatitis B — the FDA approved Hibsago (bepirovirsen) on 20 October 2026, the first antisense drug for chronic hepatitis B.
- In pooled phase 3 trials, 19% of patients achieved a functional cure, compared with none on placebo.
- A functional cure means the virus stayed undetectable for at least 24 weeks after all treatment stopped.
- The drug carries a boxed warning for serious liver reactions and low platelet counts.
Chronic hepatitis B affects around 254 million people worldwide, according to the World Health Organization, and existing treatments generally control the virus for life without clearing it. Hibsago, developed by GSK and licensed from Ionis Pharmaceuticals, works differently: it targets the genetic instructions the virus uses to make copies of itself and viral proteins, helping to reduce the amount of virus and hepatitis B surface antigen in the body.
The approval follows two phase 3 trials, B-Well 1 and B-Well 2, published in the New England Journal of Medicine. They enrolled 1,834 adults across 29 countries, all on stable antiviral therapy. A six-month course of bepirovirsen achieved a functional cure in 233 of 1,220 participants (19%), compared with 0 of 614 participants on placebo. Among patients whose baseline surface antigen levels were 1,000 IU/mL or less, the figure rose to 26%.
Who can receive it — and the risks
Hibsago is approved as an add-on to existing nucleos(t)ide analogue antiviral therapy, not a replacement for it. It is for adults without cirrhosis who have received antiviral therapy for at least six months, have suppressed hepatitis B viral DNA, and have surface antigen levels of 3,000 IU/mL or less, confirmed by an FDA-authorised test. It is injected under the skin for up to 24 weeks.
The treatment is not without risk. Hibsago carries a boxed warning for serious liver reactions, including hepatic flares, as well as low platelet counts, which can increase the risk of potentially life-threatening bleeding. The FDA granted the drug Fast Track, Breakthrough Therapy and Priority Review designations, and regulators will track durability beyond two years in post-approval studies.
What happens next
“For the first time, US patients have the potential to achieve functional cure after a six-month treatment course,” said Tony Wood, GSK’s chief scientific officer. The drug is also approved in Japan, with decisions in additional markets expected in coming months. Health Canada has approved it as a finite therapy for chronic hepatitis B. Observers will now watch for real-world data on how long the cure lasts, and for results from rival approaches in development.
For background on recent health stories, see our report on US measles cases topping 5,000 in the worst outbreak since 1991, and on a DNA discovery that could make cancer cells more vulnerable to treatment. More in our Health section.
Sources: ScienceAlert, “Breakthrough: FDA Approves First Drug Offering a ‘Functional Cure’ For Chronic Hepatitis B“; American Pharmaceutical Review, “GSK Wins FDA Approval for Hepatitis B Drug Hibsago“.