Biopharmaceutical company GSK plc (LON:GSK) (NYSE:GSK) on Thursday reported positive phase III results for bepirovirsen, its investigational treatment for chronic hepatitis B, with pooled data from the B-Well 1 and B-Well 2 trials showing a 19% functional cure rate compared with 0% in the placebo group, meeting the primary endpoint.

In patients with lower viral activity, the functional cure rate reached 26%, achieving a key secondary endpoint.

The company said 49% of patients receiving bepirovirsen achieved a hepatitis B surface antigen level of ≤100 IU/mL one year after treatment in an exploratory analysis, a level associated with increased immune control and improved outcomes. The trials also showed an acceptable safety and tolerability profile, with the most common adverse events including injection site erythema, local pain and temporary increases in liver enzyme levels.

Bepirovirsen is currently under priority review by the US Food and Drug Administration (FDA) and is also under review in Europe, Japan and China. GSK said it expects the first regulatory decisions in the third quarter of 2026 and is preparing for launch, including through a strategic collaboration with Sino Biopharmaceutical to support access in China.

GSK licensed bepirovirsen from Ionis Pharmaceuticals Inc.(Nasdaq:IONS) and the two companies have collaborated on its development.