GSK plc’s hepatitis B candidate bepirovirsen receives FDA priority review, supported by Phase III data showing improved functional cure rates over standard therapy.
Written By: Karthik Teja Macharla, PharmD
Reviewed By: Pharmacally Editorial Team
GSK plc has announced that the U.S. Food and Drug Administration has accepted for priority review its New Drug Application (NDA) for bepirovirsen, an investigational antisense oligonucleotide for the treatment of adults with chronic hepatitis B (CHB), with a target action date of 26 October 2026 under the Prescription Drug User Fee Act (PDUFA).
The therapy has also received Breakthrough Therapy Designation, supported by preliminary clinical evidence suggesting potential for meaningful improvement over existing treatments, building on Fast Track Designation granted in February 2024 to accelerate development for this serious condition with high unmet need.
A functional cure is defined as the sustained absence of hepatitis B virus (HBV) DNA and hepatitis B surface antigen (HBsAg) in the blood for at least 24 weeks after treatment cessation and is associated with a reduced risk of long-term complications, including hepatocellular carcinoma.
The regulatory submission is supported by the Phase III B-Well 1 (NCT05630807) and B-Well 2 (NCT05630820) trials, which showed that bepirovirsen combined with standard-of-care nucleos(t)ide analogues (NUCs) achieved statistically significant and clinically meaningful improvements in functional cure rates compared with standard therapy alone across all key endpoints, with greater effects observed in patients with lower baseline HBsAg levels.
The therapy demonstrated an acceptable safety and tolerability profile consistent with earlier studies.
Bepirovirsen is designed to target viral RNA involved in HBV replication, reduce viral protein production, lower HBsAg levels, and potentially restore immune control to enable sustained responses after treatment ends.
The B-Well trials were conducted across 29 countries in patients already receiving NUC-based therapy, and the molecule is also being evaluated as a potential backbone for future combination or sequential treatment strategies.
Chronic hepatitis B affects more than 250 million people worldwide and approximately 1.7 million in the United States, contributing to around 1.1 million deaths annually. Current standard treatments, typically NUCs, suppress viral replication but often require lifelong therapy and rarely achieve a functional cure.
GSK plc licensed bepirovirsen from Ionis Pharmaceuticals and continues to collaborate on its development, although the therapy is not yet approved in any market. GSK is advancing the global regulatory pathway for bepirovirsen, with the therapy now under review by the European Medicines Agency and its New Drug Application accepted in Japan.
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About the Writer
Karthik Teja Macharla, PharmD is a Pharm.D. graduate with a strong interest in clinical research, pharmacovigilance, and medical writing. In his words, he is passionate about converting complex medical information into clear, evidence-based scientific communication, committed to contributing to patient safety and advancing healthcare through accurate and impactful medical content.