GSK wins FDA green light for chronic hep B treatment Hibsago

GSK's antisense-based drug for chronic hepatitis B virus (HBV), Hibsago, has been approved in the US, its second major market after Japan, giving patients hope of a functional cure without the need for lifelong therapy.

Hibsago (bepirovirsen) has been cleared for use alongside antiviral therapies to treat adults with chronic HBV, without cirrhosis of the liver, and is the first antisense-based therapy for the disease to reach the US market. It can be used for patients who have been taking antivirals for at least six months and have suppressed levels of HBV in their blood.

"For many people living with chronic hepatitis B, treatment can mean taking antiviral medication for years to keep the virus suppressed," said Wendy Carter, acting director of the Office of Infectious Diseases in the FDA's Center for Drug Evaluation and Research (CDER). "Hibsago provides a new treatment approach that gives some patients the possibility of maintaining control of the virus after all chronic HBV treatment has ended."

The approval was granted under the FDA's priority review and breakthrough therapy designation, which GSK said recognised that Hibsago offers a "significant improvement" over the existing standard of care.

In the B-WELL trial programme, a six-month course of Hibsago achieved a functional cure response rate – which means the virus is no longer able to replicate at detectable levels – of 19%, compared to 0% with placebo.

That raises the prospect of chronic HBV becoming treatable with lifelong antiviral therapy, and a reduced risk of the complications of the condition, including liver cancer and premature death. HBV is linked to around 56% of all global liver cancer cases.

Under the approved indication, patients take GSK's drug alongside their existing hepatitis B medicine and continue that medicine for at least 24 weeks after their last Hibsago injection. Some patients may then be able to stop their existing medicine if they meet certain health and lab test requirements, said the FDA.

Around 250 million people around the world live with chronic HBV, and standard treatment with antivirals and pegylated interferons can usually only deliver a functional cure in 1% to 4% of cases.

According to Dr Chari Cohen, president of the Hepatitis B Foundation, Hibsago's approval "marks significant progress towards our aim of transforming the way [chronic hepatitis B] is managed with improvements in screening, diagnosis, and the availability of innovative treatment options for our community."

GSK is modelling peak sales of Hibsago at around £2 billion a year, and the product is a key part of its plan to drive group annual revenues above £40 billion by 2031. Along with the recent approval in Japan, the drug is also under regulatory review in other markets, including Europe and China.