GSK Wins Japan Approval for Hepatitis B Functional Cure

GSK has received approval in Japan for Hibsago (bepirovirsen), an antisense oligonucleotide (ASO) treatment designed to provide a functional cure for chronic hepatitis B (CHB) in adults.

Japan’s Ministry of Health, Labour and Welfare (MHLW) approved Hibsago for adults with chronic hepatitis B who have received at least six months of prior nucleos(t)ide analogue treatment and meet specific viral marker requirements. The approval marks the first global approval of bepirovirsen and makes Hibsago the first and only treatment approved in Japan as a functional cure for CHB.

Chronic hepatitis B remains a major global health problem and is a leading cause of liver cancer. In Japan, nearly one million people are estimated to live with the disease, which is linked to around 4,000 deaths each year.

The approval is supported by results from GSK’s B-Well Phase III trials. In the studies, six months of treatment with bepirovirsen produced a functional cure in 19% of adults with hepatitis B surface antigen (HBsAg) levels of up to 3,000 IU/ml. This compared with no functional cure responses in the placebo groups during the trial period.

Functional cure was defined as hepatitis B virus DNA and HBsAg remaining undetectable for at least 24 weeks after treatment ended. Achieving this response could allow some patients to stop long-term treatment while maintaining control of the infection.

The trials also found stronger results among patients with lower HBsAg levels. Among adults with HBsAg levels of up to 1,000 IU/ml, 26% achieved a functional cure following treatment with bepirovirsen. This group represents about 45% of diagnosed chronic hepatitis B cases worldwide.

Additional analyses showed that 49% of patients in the overall study population had reduced their HBsAg levels to 100 IU/ml or below by week 72. The figure increased to 62% among patients who started with HBsAg levels of up to 1,000 IU/ml.

GSK said the safety and tolerability results were consistent with earlier studies of bepirovirsen. The most common side effects included redness at the injection site, local pain and temporary increases in liver enzyme levels.

Tony Wood, Chief Scientific Officer at GSK, said the approval gives people living with chronic hepatitis B in Japan access to a treatment designed to achieve a functional cure. He added that the company expects the treatment could help some patients move away from lifelong therapy and lower the risk of long-term complications.

The Japanese approval was supported through the country’s SENKU designation, which is given to innovative medicines that could address significant unmet medical needs.

GSK is continuing regulatory submissions for bepirovirsen in other countries. Regulatory decisions, including in the United States, are expected in the coming months. The company is also studying bepirovirsen in future sequential treatment approaches for chronic hepatitis B.