Hibsago approved for chronic hepatitis B, advancing the goal of functional cure

Clinical takeaway: Consider bepirovirsen for appropriate patients with virologically controlled chronic hepatitis B who are interested in a finite treatment approach; some patients achieved durable off-treatment viral control after discontinuing antiviral therapy.

FDA has approved Hibsago (bepirovirsen) for adults without cirrhosis who have been taking HBV antiviral therapy for at least six months, have suppressed HBV DNA, and have hepatitis B surface antigen (HBsAg) levels of 3,000 IU/mL or less, as determined by an FDA-authorized test.

Hibsago is the first FDA-approved antisense oligonucleotide for chronic hepatitis B. Current antiviral therapies can effectively suppress HBV replication but typically require long-term treatment and seldom allow patients to discontinue therapy. Bepirovirsen targets HBV ribonucleic acid (RNA) transcripts, reducing production of viral proteins, including HBsAg, and may help restore immune control of infection after treatment ends.

Approval was supported by the phase 3 B-WELL 1 and B-WELL 2 trials. Functional cure, defined as sustained HBV DNA suppression and loss of detectable HBsAg for at least 24 weeks after discontinuation of all hepatitis B therapy, was achieved in 20% of patients receiving bepirovirsen in B-WELL 1 and 19% in B-WELL 2, compared with none of those receiving placebo. Benefits were greatest among patients with baseline HBsAg levels of 1,000 IU/mL or less, with functional cure rates of 25% and 28%, respectively.

Across both trials, 24% of bepirovirsen recipients met criteria to discontinue background antiviral therapy, whereas no placebo-treated patients did. Twenty-four weeks after stopping all hepatitis B therapy, nearly one in five treated patients maintained viral suppression and remained HBsAg-negative, meeting the study definition of functional cure.

Hibsago is administered as a subcutaneous injection for up to 24 weeks while patients continue their existing antiviral therapy. Following the first dose, subsequent injections may be self-administered when appropriate.

Hibsago carries a boxed warning for serious liver reactions and thrombocytopenia that may increase the risk of life-threatening bleeding. Additional warnings include worsening kidney function, serious inflammatory adverse reactions such as vasculitis, and risks associated with improper administration. The most common adverse reactions were injection-site reactions, fever, fatigue, and headache.

Wendy Carter, DO, Acting Director of the Office of Infectious Diseases in the Center for Drug Evaluation and Research said “Hibsago provides a new treatment approach that gives some patients the possibility of maintaining control of the virus after all chronic HBV treatment has ended. This approval represents an important advance for people living with this serious disease.”.

Sources: FDA (2026 Oct 20). FDA approves first-of-its-kind chronic hepatitis B treatment; GSK. (2026 Oct 20). Hibsago (bepirovirsen) approved in the US for the treatment of chronic hepatitis B (CHB)