The US Food and Drug Administration (FDA) has approved GSK’s Hibsago (bepirovirsen), marking the first functional cure available to hepatitis B patients in the US.
The drug will be available for patients without cirrhosis, already receiving nucleos(t)ide analogue reverse transcriptase inhibitor (NRTI) therapy for at least six months who have suppressed HBV deoxyribonucleic acid (DNA), and hepatitis B virus (HBV) surface antigen (HBsAg) levels below a certain amount. If patients meet these requirements, Hibsago is given alongside the NRTI therapy.
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The approval marks a significant moment for US patients with the chronic form of the liver disease, who need to take daily antiviral pills or immune-modulating injections. Chronic hepatitis B is a long-term liver infection caused by HBV. Over time, the infection can lead to serious liver disease, including cirrhosis, and increase the risk of liver cancer.
Hibsago is the first FDA-approved antisense oligonucleotide (ASO) to treat chronic hepatitis B, according to the agency. The drug netted its first regulatory approval in Japan in August 2026.
Hibsago works by targeting the genetic material of HBV in liver cells so it can be used by the virus to make viral proteins and support viral replication. This lowers the amount of virus and hepatitis B surface antigen in the body. Hibsago is injected under the skin for up to 24 weeks.
Results from GSK’s Phase III trials (NCT05630807; NCT05630820) demonstrated that 19% of patients had undetectable levels of hepatitis B virus after receiving the drug for half a year, indicating the disease is controlled by the immune system without medication. This is known as a functional cure, which is only achieved in around 1% of cases treated with standard of care (SoC).
GSK’s chief scientific officer, Tony Wood, said: “Despite current therapies, many people living with chronic hepatitis B remain on treatment indefinitely and continue to face the risk of serious liver complications. For the first time, with Hibsago, US patients have the potential to achieve functional cure after a six-month treatment course, with the added convenience of the option of self-administration after the first dose.”
While Hibsago showed acceptable safety and tolerability, the drug does come with two boxed warnings. One is the potential to cause serious liver reactions, and the other is its ability to cause low blood platelet numbers. In some cases, the latter – known as thrombocytopenia – can be life-threatening.
Citi analysts said the thrombocytopenia boxed warning was “less expected”, though they maintained a blockbuster sales prediction for the treatment, calling both warnings “manageable”.
GSK expects peak annual sales of more than £2bn ($2.68bn) for Hibsago, with the product a key driver to the drugmaker’s wider aims of reaching more than £40bn in annual revenue by 2031.
Analysis by GlobalData’s Pharma Intelligence Centre predicts Hibsago will become a blockbuster drug in 2032.
GlobalData is the parent company of Pharmaceutical Technology.
