GSK plc said its experimental hepatitis B therapy bepirovirsen received its first global approval from Japan’s Ministry of Health, Labour and Welfare as a functional cure for chronic hepatitis B in adult patients.
The drug, known commercially as Hibsago, is approved for adults who have completed at least six months of nucleos(t)ide analogue therapy and meet specific viral marker criteria. Japan’s regulator granted the clearance under its SENKU designation, which fast-tracks treatments for conditions with high unmet medical needs.
Nearly one million people in Japan live with chronic hepatitis B, a disease linked to approximately 4,000 deaths annually in the country. GSK licensed bepirovirsen from Ionis Pharmaceuticals and co-developed the antisense oligonucleotide, which works by inhibiting the production of hepatitis B virus genetic components.
Regulatory submissions for bepirovirsen are ongoing in multiple markets, with decisions expected in the coming months, including in the United States. The approval follows results from the B-Well phase III trials, conducted across 29 countries with 1,220 participants receiving the drug and 614 in the placebo group.
In the trials, functional cure—defined as undetectable hepatitis B virus DNA and viral protein HBsAg for at least 24 weeks after treatment—was achieved by 19% of adults with HBsAg levels of 3,000 IU/ml or lower. Current standard-of-care therapies typically achieve a 1% functional cure rate after one year. Among participants with HBsAg levels of 1,000 IU/ml or lower—a subgroup representing roughly 45% of global chronic hepatitis B cases—the functional cure rate reached 26%, based on data from 768 participants.
