FDA Approves Bepirovirsen as First Antisense Therapy for Chronic Hepatitis B

The FDA approved Hibsago (bepirovirsen) on October 20, 2026, as the first antisense oligonucleotide treatment for chronic hepatitis B, intended for use with nucleos(t)ide analogue therapy in adults without cirrhosis. Clinical trial data from the B-Well 1 and B-Well 2 studies showed 19% of patients achieved functional cure, defined as undetectable virus for 24 weeks after stopping all treatment, compared with 0% for placebo. The drug carries boxed warnings for hepatic flares and thrombocytopenia, requiring weekly platelet monitoring. The treatment involves subcutaneous injections for up to 24 weeks, with patients continuing antiviral medication for at least 24 weeks afterward. GSK estimates 1.7 million Americans live with chronic hepatitis B, and Japan has already approved the drug.