GSK Wins FDA Approval for Hibsago to Treat Chronic Hepatitis B

GSK has received approval from the US Food and Drug Administration (FDA) for Hibsago (bepirovirsen), a new treatment for certain adults living with chronic hepatitis B. The approval marks an important step in the treatment of the long-term viral infection, which can lead to serious liver damage and liver cancer.

Announced on October 20, 2026, the approval allows Hibsago to be used alongside existing antiviral medicines in adults who do not have cirrhosis, have been receiving antiviral treatment for at least six months, and have controlled levels of the hepatitis B virus in their blood. Patients must also meet specific criteria for hepatitis B surface antigen (HBsAg) levels.

Hibsago is the first antisense oligonucleotide approved by the FDA for chronic hepatitis B. It is designed to target the genetic instructions used by the virus to produce viral components. By reducing viral proteins and hepatitis B surface antigen, the treatment may help the body’s immune system regain control of the infection.

The approval was supported by results from two Phase 3 clinical trials, B-Well 1 and B-Well 2. Combined results showed that 19% of patients receiving bepirovirsen achieved a functional cure, compared with none in the placebo group. The analysis included adults with baseline HBsAg levels of 3,000 IU/mL or lower.

Among patients with HBsAg levels of 1,000 IU/mL or lower, the functional cure rate reached 26%. This group represents a substantial proportion of people diagnosed with chronic hepatitis B worldwide.

A functional cure means that hepatitis B viral DNA and the surface antigen are no longer detectable for at least 24 weeks after all treatment has stopped. While this does not mean the virus has been completely removed from the body, it indicates that the infection can remain under control without ongoing medication.

Many people with chronic hepatitis B currently need long-term, and often lifelong, antiviral treatment to keep the virus suppressed. Although existing medicines can control the infection, they do not usually eliminate the need for continued therapy. Hibsago could offer some eligible patients the possibility of maintaining control of the disease after completing a defined course of treatment.

The treatment is administered by injection over six months, with the option for patients to self-administer after their first dose. Patients must continue their existing antiviral medicines during treatment and for at least 24 weeks after their final Hibsago injection. Stopping existing therapy depends on meeting the required clinical and laboratory criteria.

GSK’s approval also highlights the growing role of antisense oligonucleotide technology in developing new treatments for viral diseases. The company licensed bepirovirsen from Ionis Pharmaceuticals and worked with the company on its development.

However, Hibsago carries important safety risks, including potentially serious liver reactions and low platelet counts, which can increase the risk of bleeding. Healthcare professionals must monitor patients closely through regular blood tests during treatment.

GSK plans to continue pursuing regulatory approvals for bepirovirsen in other countries. The US approval could represent a significant development in chronic hepatitis B care, offering eligible patients a new approach with the potential for long-term viral control after treatment ends.