GSK plc said on Monday its experimental hepatitis B treatment Hibsago (bepirovirsen) received its first global approval from Japan's Ministry of Health, Labour and Welfare.
The approval, granted under the SENKU designation for innovative therapies addressing high-priority unmet needs, covers adult patients with chronic hepatitis B who have completed at least six months of nucleos(t)ide analogue therapy and meet specific viral marker thresholds.
Japan's decision follows Phase III B-Well trial results, which enrolled 1,834 participants across 29 countries. In the general study population with HBsAg levels of 3,000 IU/ml or lower, bepirovirsen achieved a 19% functional cure rate after one year, compared with about 1% under standard-of-care alone. Among the subset with HBsAg levels of 1,000 IU/ml or lower—which accounts for roughly 45% of global chronic hepatitis B cases—the cure rate reached 26%.
A functional cure is defined as sustained undetectability of hepatitis B virus DNA and the viral protein HBsAg for at least 24 weeks after treatment cessation. GSK licensed the antisense oligonucleotide from Ionis Pharmaceuticals and co-developed the therapy.
The drugmaker noted that regulatory submissions are underway in multiple regions, with decisions expected in the coming months, including in the United States. Japan's approval comes amid an estimated one million chronic hepatitis B cases in the country, contributing to approximately 4,000 deaths annually.
