In late‑stage trials published in the New England Journal of Medicine, the experimental hepatitis B drug bepirovirsen produced a functional cure in roughly 20% of participants, allowing them to stop all medication without viral rebound. The studies, conducted by GSK and Ionis Pharmaceuticals, involved 1,838 adults who received weekly injections for six months followed by a six‑month observation period.

20% functional cure rate in bepirovirsen trials

According to the trial data, about one‑fifth of patients who completed the bepirovirsen reigmen maintained undetectable hepatitis B DNA after therapy stopped , a result not seen in any placebo recipient. Researchers describe this outcome as a "functional cure" because the virus remains suppressed without ongoing antiviral pills.

FDA decision expected by October

The U.S.. Food and Drug Administration is reviewing the bepirovirsen application, with a verdict anticipated by October, the source reports. If approved, bepirovirsen would be the first drug to offer a functional cure to a meaningful segment of the more than 250 million people living with chronic hepatitis B worldwide.

1,838 participants received weekly injections

The two large‑scale studies enrolled 1,838 participants who were already on standard antiviral therapy. Over six months,they received weekly sub‑cutaneous doses of bepirovirsen or a matching placebo, after which those with at least six months of undetectable viral load were allowed to discontinue all medication.

GSK and Ionis partner on bepirovirsen

GSK and Ionis Pharmaceuticals co‑developed bepirovirsen, a molecule that binds hepatitis B viral RNA and blocks production of new virus particles and the surface antigen that helps the virus evade immune detection. the source notes that the drug’s mechanism represents a shift from merely suppressing viral replication to actively reducing the virus’s genetic material.

Will the functional cure durability hold beyond 12 months?

Experts caution that longer‑term follow‑up is needed to confirm whether the 20% cure rate persists beyond the 12‑month study window. The report also highlights that safety data, including potential side effects, remain under srcutiny as regulators weigh approval .