Experimental Hepatitis B Drug Offers Functional Cure in Clinical Trials

A groundbreaking experimental drug for chronic hepatitis B has shown promising results in two international clinical trials, offering a so-called 'functional cure' to about one in five patients. The drug, bepirovirsen (nicknamed 'bepi'), is developed by GSK and Ionis Pharmaceuticals and is currently under fast-track review by the U.S.

Food and Drug Administration, with a decision expected in October. Regulators in Japan, China, and Europe are also evaluating the drug.

Chronic hepatitis B, which affects over 250 million people worldwide and about 1.7 million in the U.S., can lead to liver cancer or liver failure and kills approximately 1.1 million people annually. Current treatments require lifelong daily pills that suppress the virus but do not eliminate it, as the virus can hide in the body and rebound if therapy stops.

The trials involved 1,838 patients who received either weekly injections of bepirovirsen or a placebo for six months, alongside their regular antiviral pills. After stopping the injections, patients whose virus remained undetectable for six months could also stop their daily pills.

About 20% of those who received bepirovirsen achieved a functional cure—meaning the virus remained undetectable for six months after stopping all treatment—while no patients in the placebo group achieved this outcome.

Dr. Seng Gee Lim of the National University Health System of Singapore, who led the GSK-funded studies, called the results a significant step forward.

'We have not had a treatment which has come to this level of cure,' he said. Dr.

Anna Lok, a hepatitis expert at the University of Michigan, noted in the New England Journal of Medicine that the findings represent a major advance but cautioned that more research is needed to determine the durability of the remission-like state.

Side effects included mild injection-site redness or pain and a temporary rise in liver enzymes. The trials did not include patients with cirrhosis, high levels of the S protein, or other complicating factors.

GSK has tracked a small number of patients from earlier studies and found that most maintained the functional cure for up to three years.