GSK said the FDA has approved Hibsago, also known as bepirovirsen, for certain adults with chronic hepatitis B, based on trials showing some patients achieved disease control after stopping treatment.
The approval covers use alongside nucleos(t)ide analogue antiviral therapy in adults without cirrhosis who have received that therapy for at least six months. Patients must have suppressed hepatitis B viral DNA and surface antigen levels of 3,000 international units per milliliter or less, measured using an FDA-authorized test.
Hibsago is administered over six months, with patients able to self-administer after the first dose.
Pooled results from the Phase 3 B-Well trials showed functional cure in 19% of bepirovirsen recipients, or 233 of 1,220 participants, compared with none of 614 receiving placebo.
Functional cure meant viral DNA and hepatitis B surface antigen remained undetectable for at least 24 weeks after all treatment stopped, indicating immune control without medication.
Among participants whose starting surface antigen levels were 1,000 units per milliliter or less, 26% achieved functional cure, compared with none receiving placebo.
The most frequently reported adverse events were injection-site redness, local pain and temporary increases in a liver enzyme.
Bepirovirsen targets viral RNA to reduce production of hepatitis B proteins and surface antigen, potentially helping the immune system regain control.
GSK licensed the drug from Ionis Pharmaceuticals and collaborated on development. The company said bepirovirsen is also approved in Japan, with regulatory decisions in additional markets anticipated in coming months.
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