GSK’s bepirovirsen granted priority review and breakthrough therapy designation by FDA for chronic hepatitis B

GSK has announced that the FDA has accepted its new drug application for bepirovirsen, an investigational antisense oligonucleotide therapy for adults with chronic hepatitis B, and granted it priority review status. The agency has also awarded the drug Breakthrough Therapy Designation, recognising its potential to offer substantial improvement over existing treatments. A PDUFA date of 26 October 2026 has been assigned.

The designation adds to a Fast Track Designation bepirovirsen already received in February 2024, and reflects the significant unmet need in chronic hepatitis B. The disease affects more than 250 million people worldwide and around 1.7 million in the United States. Current standard of care, typically nucleoside analogues, often requires lifelong treatment, with functional cure rates of just around 1%.

Functional cure, defined as undetectable hepatitis B virus DNA and surface antigen in the blood for at least 24 weeks after stopping all treatment, is associated with meaningful reductions in long-term complications including liver cancer, which chronic hepatitis B is a leading cause of globally.

The regulatory submission is supported by results from the Phase III B-Well 1 and B-Well 2 trials, in which bepirovirsen demonstrated statistically significant and clinically meaningful functional cure rates. Bepirovirsen plus standard of care outperformed standard of care alone across all ranked endpoints, with an even greater effect observed in patients with lower baseline hepatitis B surface antigen levels. The safety and tolerability profile was consistent with earlier studies.

Full data from the B-Well trials are expected to be presented at the European Association for the Study of Liver Congress and submitted for peer reviewed publication in 2026.

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chronic hepatitis b, FDA for chronic hepatitis B, GSK, GSK China, GSK's bepirovirsen, hepatitis B