GSK has secured approval from the US Food and Drug Administration (FDA) for Hibsago, a first-in-class treatment for chronic hepatitis B that can achieve functional cure after just six months of therapy.
Hibsago, known chemically as bepirovirsen, is the first drug to offer meaningful rates of functional cure in chronic hepatitis B, a viral liver disease affecting around 1.7 million people in the United States.
The approval was granted under priority review and Breakthrough Therapy Designation, reflecting the drug's significant advantage over existing standard-of-care treatments.
Phase III trial data showed Hibsago achieved a functional cure rate of 19% in eligible patients, compared with less than 1% for current standard-of-care therapy alone.
Functional cure means both viral DNA and the hepatitis B surface antigen become undetectable for at least 24 weeks after stopping all treatment, indicating the immune system has regained control without medication.
In patients with lower baseline levels of the surface antigen, the cure rate reached 26%, a result GSK described as clinically meaningful.
GSK chief scientific officer Tony Wood said that for the first time US patients had the potential to achieve functional cure after a six-month course, with the option of self-administration after the first dose.
Bepirovirsen is an antisense oligonucleotide (ASO), a type of drug that works by blocking the genetic machinery the hepatitis B virus uses to replicate and produce proteins that suppress the immune response.
GSK licensed bepirovirsen from Ionis Pharmaceuticals and is advancing regulatory submissions across multiple geographies, with further decisions expected in the coming months.
