U.S. approves Hepsago for hepatitis B with injections for up to 24 weeks
Key Facts
The U.S. Food and Drug Administration on 20 October 2026 approved GSK's Hepsago for chronic hepatitis B, offering some patients the possibility of controlling the infection after stopping treatment. The drug, known generically as bepirovirsen, is used alongside antiviral therapy in the patient group covered by the regulatory approval. It is administered by injection under the skin for up to 24 weeks alongside standard hepatitis medication, according to the FDA's statement. The company said patients can administer the treatment themselves after the first dose. Tony Wood, GSK's chief scientific officer, said "U.S. patients now have the possibility of achieving a functional cure" with the drug.
The approval covers adults with chronic hepatitis B without cirrhosis, under conditions announced by the FDA. Patients must have received antiviral treatment for at least 6 months before starting Hepsago. Blood levels of the virus must also be suppressed when patients are selected for treatment. The approval sets a hepatitis B surface antigen ceiling of 3000 international units per millilitre. This antigen level must be measured using an FDA-approved test as part of the treatment eligibility requirements.
In the two clinical trials, 24% of Hepsago recipients met the criteria for stopping their standard hepatitis medication, according to the FDA. At 24 weeks after stopping all treatment for the disease, the virus remained under control and surface antigen was no longer detectable in the blood of 19% of drug recipients. GSK defines a functional cure as sustained undetectable levels of viral DNA and surface antigen in the blood for at least 24 weeks after stopping all treatment. Among participants with lower viral activity, the functional cure rate reached 26%, compared with 0% among those receiving standard care alone, according to the company's results. GSK says standard care often requires lifelong treatment, while fewer than 1% of patients achieve a functional cure.
The approval includes a boxed warning for serious liver reactions associated with the drug, according to the FDA. The warning also covers the possibility of a decline in platelet counts among patients receiving treatment. Such a decline may increase the risk of life-threatening bleeding, according to the agency's drug safety statement. Chronic hepatitis B affects about 1.7 million people in the United States, according to the estimate cited by Ionis in its approval announcement. Globally, more than 240 million people have the disease, according to GSK's statement on the pivotal trial results.
The drug's pivotal trial programme included more than 1800 patients from 29 countries, according to GSK. The company announced positive initial results from these trials on 7 January 2026, before the drug progressed through regulatory review and approval milestones. The results were published in the New England Journal of Medicine alongside their presentation at the European Association for the Study of the Liver congress. Hepsago received its first approval worldwide in Japan, according to the company's announcement dated 24 August 2026. In the United States, the target date for the FDA's decision on the approval application had been 26 October 2026, according to GSK's earlier regulatory review announcement.
On the commercial front, GSK licensed the drug from Ionis in 2019, according to Ionis's statement on the U.S. approval. Under the agreement, Ionis is entitled to tiered royalties ranging from 10% to 12% of net sales of bepirovirsen. The agreement also provides for milestone payments to the company when the relevant conditions are met. GSK said it continues to submit applications for the drug in multiple markets and expects significant regulatory decisions in the coming months. The company plans to announce third-quarter results on 28 October 2026, the next financial milestone for investors following the U.S. approval.