FDA approves Hibsago (bepirovirsen), the first antisense drug for chronic hepatitis B

The US Food and Drug Administration on 20 October 2026 approved Hibsago (bepirovirsen), an injection from GSK, used together with existing antiviral therapy to treat chronic hepatitis B in certain adults without cirrhosis. It is the first FDA-approved antisense oligonucleotide for the disease — a drug that targets the genetic instructions the virus uses to copy itself and make viral proteins.

Who it is for

Adults who have taken hepatitis B antivirals for at least six months, have suppressed virus levels in the blood and a hepatitis B surface antigen (HBsAg) level of 3,000 IU/mL or less, measured with an FDA-authorised test. The FDA also authorised a Roche companion test for this purpose.

The trial results

• Hibsago was compared with placebo in two clinical trials. It is injected under the skin for up to 24 weeks alongside usual medication, which continues for at least 24 weeks after the last injection.
• 24% of patients on Hibsago met the requirements to stop their existing medicine, versus none on placebo.
• 24 weeks after stopping all hepatitis B treatment, 19% of Hibsago patients still had the virus under control and no detectable HBsAg.

Safety and limitations

Hibsago carries a boxed warning for serious liver reactions and low platelet counts that can raise the risk of life-threatening bleeding, plus warnings about kidney function and serious inflammatory reactions such as vasculitis. Common side effects include injection-site reactions, fever, fatigue and headache. The figures come from the FDA announcement; most patients in the trials did not reach treatment-free control, and the follow-up described (24 weeks off treatment) is short relative to a lifelong infection. Patients should discuss options with their doctor.