- PDUFA date set for 26 October 2026; FDA granted Breakthrough Therapy and Fast Track designations to bepirovirsen.
- Phase III B-Well 1 and 2 (randomized, double-blind, placebo-controlled across 29 countries) showed significantly higher functional cure rates versus standard of care in patients with baseline HBsAg <=3000 IU/ml.
- GSK licensed bepirovirsen from Ionis; it is a triple-action antisense oligonucleotide targeting HBV mRNA and pregenomic RNA and is not approved anywhere.
Regulatory status
FDA has accepted an NDA for bepirovirsen for adults with chronic hepatitis B and granted Breakthrough Therapy Designation in addition to an earlier Fast Track designation (Feb 2024); the PDUFA goal date is 26 October 2026.
Clinical evidence
Phase III B-Well 1 and 2 (randomised, double-blind, placebo-controlled, 29 countries) showed statistically significant and clinically meaningful higher functional cure rates for bepirovirsen plus standard of care versus standard of care alone, including greater effects in patients with lower baseline HBsAg; safety and tolerability were consistent with prior studies and data will be presented at EASL and submitted for peer review in 2026.
Disease context
Chronic hepatitis B affects more than 250 million people worldwide (about 1.7 million in the US) and often requires lifelong nucleos(t)ide analogue therapy; functional cure—undetectable HBV DNA and HBsAg for at least 24 weeks off treatment—is rare with current care and linked to reduced risk of long-term complications including liver cancer.
Drug profile and development
Bepirovirsen is a triple-action antisense oligonucleotide that targets HBV mRNA and pregenomic RNA to inhibit replication, reduce HBsAg and stimulate immune responses; GSK licensed the asset from Ionis, it is being evaluated as a potential backbone for sequential regimens and is not approved anywhere.
