GSK’s bepirovirsen has been accepted for FDA Priority Review with Breakthrough Therapy designation, with an action date of October 26, 2026, Ionis Pharmaceuticals announced.

Bepirovirsen is an investigational antisense oligonucleotide for chronic hepatitis B. It is designed to cut viral replication, suppress hepatitis B surface antigen and stimulate the immune system toward a functional cure, Morningstar reported.

The application rests on the Phase 3 B-Well 1 and B-Well 2 trials, run across 29 countries. Bepirovirsen plus standard of care delivered significantly higher functional cure rates than standard of care alone across all ranked endpoints.

Chronic hepatitis B affects more than 250 million people worldwide and about 1.7 million in the US. Current therapies often require lifelong treatment with functional cure rates of only around 1 percent.

“As the first medicine to deliver clinically meaningful functional cure rates, bepirovirsen is uniquely positioned,” said Ionis CEO Brett Monia. Reviews are also underway in Europe, China and Japan.