On October 20, 2026, the FDA approved GSK's Hibsago (bepirovirsen) for non-cirrhotic adults with chronic hepatitis B taking antivirals, making it the first approved antisense oligonucleotide for the infection. Phase III trials showed nearly 20% of patients achieved a functional cure after six months of therapy. The drug carries a boxed warning for hepatic flares and low platelet counts, requiring routine blood monitoring. GSK projects peak sales over $2.68 billion.
FDA approval and administration details
- ▪The FDA approved GSK's Hibsago (bepirovirsen) on October 20, 2026, as an antisense oligonucleotide therapy for adults with chronic hepatitis B who lack cirrhosis and are taking antiviral therapy
- ▪Hibsago is administered as a six-month treatment course and can be self-administered after the patient receives the initial dose
- ▪The FDA indication requires Hibsago to be administered alongside nucleos(t)ide analog reverse transcriptase inhibitors in patients with suppressed hepatitis B virus levels and surface antigen levels of 3,000 IU/mL or less
Phase III trial efficacy results
- ▪In B-Well 1 and B-Well 2 Phase III trial participants with hepatitis B surface antigen levels of 1,000 IU/mL or less, Hibsago achieved a functional cure rate of 26% at week 72
- ▪Phase III B-Well 1 and B-Well 2 trials showed that 19% to 20% of chronic hepatitis B patients with surface antigen levels of 3,000 IU/mL or less achieved a functional cure at week 72 with Hibsago, compared to none in the placebo group
Boxed warnings and safety risks
- ▪Prescribing warnings for Hibsago include risks of deteriorating kidney function, serious inflammatory adverse reactions such as vasculitis, and complications from improper injection
- ▪The FDA approved Hibsago with a boxed warning regarding risks of serious hepatic flares during treatment and low platelet counts that can cause life-threatening thrombocytopenia
Adverse effects and patient monitoring
- ▪The most common adverse effects reported for Hibsago are injection site reactions, fatigue, fever, and headache
- ▪Patients using Hibsago require regular blood tests during therapy to monitor for hepatic flares, reduced platelet counts, and kidney function risks
Commercial outlook and global regulatory status
- ▪GSK licensed Hibsago from Ionis Pharmaceuticals, which remains eligible for milestone payments following regulatory approvals and benchmark achievements
- ▪Hibsago has secured regulatory approval in Japan and is under regulatory review by health authorities in China and Europe
- ▪GSK projects peak annual sales exceeding £2 billion ($2.68 billion) for Hibsago as part of its strategy to reach £40 billion in annual revenue by 2031 under CEO Luke Miels
Hepatitis B burden and standard care limitations
- ▪More than 250 million people globally live with chronic hepatitis B, which causes over half of liver cancer cases worldwide and can lead to liver damage and cirrhosis
- ▪Standard-of-care nucleotide analogue treatments suppress hepatitis B but achieve a sustained functional cure in only 1% to 4% of patients, often requiring lifelong administration
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