FDA approves GSK's Hibsago for chronic hepatitis B

The FDA announced on October 20, 2026 that it had cleared Hibsago (bepirovirsen) for use alongside existing antiviral therapy in certain adults with chronic hepatitis B who do not have cirrhosis. Hibsago is the first FDA-approved antisense oligonucleotide for chronic hepatitis B and is intended for adults who have been on HBV antiviral therapy for at least six months, have suppressed HBV levels in their blood, and have hepatitis B surface antigen (HBsAg) levels of 3,000 IU/mL or less, as confirmed by an FDA-authorized test.¹

The drug interferes with the virus's ability to replicate and produce viral proteins, which lowers both viral load and surface antigen levels in the body, according to the FDA. Alongside the approval, the FDA authorized the Roche Elecsys HBsAg II quant II RxDx assay as a companion diagnostic to help select patients for antiviral therapy and to monitor them during treatment.¹

The approval rests on two placebo-controlled trials in which patients received Hibsago by subcutaneous injection for up to 24 weeks, continued their existing hepatitis B medicine for at least 24 weeks after the last injection, and in some cases could then stop that medicine if they met certain health and lab criteria.¹ Across the two trials, 24% of Hibsago patients met the criteria to stop their existing medicine, compared with none on placebo.¹ Twenty-four weeks after stopping all hepatitis B treatment, 19% of Hibsago patients still had viral control and undetectable HBsAg.¹

Hibsago carries a boxed warning for serious liver reactions and low platelet counts that can raise bleeding risk, plus warnings about worsening kidney function, inflammatory reactions such as vasculitis, and risks tied to improper injection.¹ The most common side effects besides lab abnormalities were injection site reactions, fever, fatigue and headache.¹

The FDA had granted Hibsago Fast Track, Breakthrough Therapy, and Priority Review designations, and the approval was granted to GSK plc.¹