Japan approves GSK's Hibsago as first functional cure for chronic hepatitis B

Japan's Ministry of Health, Labour and Welfare has approved GSK's Hibsago (bepirovirsen) as a treatment for chronic hepatitis B, the company announced on August 24, 2026. The approval covers adult patients who have received at least six months of prior nucleos(t)ide analogue therapy and meet pre-defined viral markers.¹ This marks the first global approval for bepirovirsen and the first functional cure treatment for chronic hepatitis B approved in Japan.¹

Chronic hepatitis B is a major public health challenge and a leading cause of liver cancer globally, and in Japan nearly one million people live with the disease, contributing to around 4,000 deaths annually.¹ The approval was accelerated through Japan's SENKU designation, given to innovative medicines addressing high unmet medical need.¹

The approval rests on results from the Phase III B-Well trials. Pooled data showed that six-month treatment with bepirovirsen achieved a statistically significant 19% functional cure response rate (233 of 1,220 versus 0 of 614 in the placebo group; p<0.001 in both trials) in the overall study population, meeting the primary endpoint.¹ In a key secondary endpoint, a functional cure rate of 26% (200 of 768 versus 0 of 393 in placebo; p<0.001 in both trials) was reached in participants with baseline HBsAg of 1000 IU/ml or less.¹

The trials showed an acceptable safety and tolerability profile consistent with prior studies, with the three most common adverse events being injection site erythema, local pain, and a temporary rise in a liver enzyme.¹

GSK licensed bepirovirsen from Ionis and has collaborated with the company on its development.¹ Regulatory submissions continue in additional geographies, including the United States, with decisions expected in the coming months.¹