U.S. approves Hepsago for hepatitis B with injections for up to 24 weeks
Key Facts
The U.S. Food and Drug Administration announced its approval of Hepsago injections, the brand name for GSK's bepirovirsen, to treat chronic hepatitis B. In a statement announcing the decision, the agency said the treatment is administered by subcutaneous injection for up to 24 weeks, in combination with antiviral therapy. The approval is limited to a specific group of adults with the disease who do not have cirrhosis. The drug carries a boxed warning about serious liver reactions and low platelet counts. The approval allows its use in this group as part of a regimen combining it with antiviral drugs.
According to results announced by GSK, the functional cure rate was 19% across all participants who received bepirovirsen in addition to standard treatment. The rate rose to 26% among patients with lower viral activity, a subgroup of trial participants. By comparison, the functional cure rate was 0% among those receiving standard treatment alone in the comparison reported by the company. The pivotal trials included more than 1,800 patients from 29 countries, according to the company's statement on its results. The results concerned functional cure in a subset of participating patients, with the rate differing between the overall population and the group with lower viral activity.
GSK defines functional cure as viral DNA and surface antigen remaining undetectable in the blood after all treatments have been stopped. This definition requires that condition to persist for at least 6 months after treatment ends. On bepirovirsen's mechanism, the company said it was "designed to recognise and destroy the genetic components of the hepatitis B virus". The components targeted by the drug are the virus's RNA, according to the company's description of how it works. It added that destroying these components may allow the immune system to regain control of the virus, the effect the treatment approach seeks to achieve.
The drug enters a treatment field in which GSK says standard medicines, nucleoside or nucleotide analogues, often require lifelong use. Functional cure rates with these treatments are typically just 1%, according to the treatment background provided by the company. Untreated chronic hepatitis B can lead to liver damage and cirrhosis, according to the U.S. Centers for Disease Control and Prevention. Its potential complications also include liver cancer and death, the CDC says, highlighting the health burden associated with persistent, untreated chronic infection. In China alone, GSK estimates that about 75 million people have the disease, according to an estimate cited in a statement on the drug's regulatory review there.
The U.S. move followed approval in Japan, announced by GSK on 24 August 2026, for Hepsago to treat chronic hepatitis B. In its announcement of the Japanese approval, the company described the drug as "the first and only treatment to achieve a functional cure for chronic hepatitis B". In the U.S. regulatory process, the new drug application had been accepted for priority review by the FDA. Bepirovirsen also received breakthrough therapy designation from the agency, according to GSK's statement on the review. The agency had set 26 October 2026 as its target date for a decision on the application, before announcing approval of the injections.
On the commercial side, GSK licensed bepirovirsen from Ionis in 2019 under a joint development and licensing agreement. The agreement provides for tiered royalties payable to Ionis on net sales of the drug, according to the company's statement. Those royalties range between 10 and 12%, linking Ionis's commercial returns to sales of the treatment licensed to GSK. The U.S. approval comes ahead of GSK's next earnings release, scheduled for publication through the London Stock Exchange. The company has set 28 October 2026 for its third-quarter results, the next event on its financial reporting calendar.