Ionis partner GSK announces Hibsago (bepirovirsen) approved in the U.S. for the treatment of chronic hepatitis B (CHB)

– Approval based on Phase 3 data showing unprecedented functional cure rates compared to standard of care –
– Six-month treatment with option of at-home administration after first dose –
– CHB affects approximately 1.7 million people in the U.S. –

CARLSBAD, Calif., October 21, 2026--Ionis Pharmaceuticals, Inc. (Nasdaq: IONS) partner GSK today announced that the U.S. Food and Drug Administration (FDA) has approved Hibsago (bepirovirsen) for the treatment of chronic hepatitis B (CHB) virus infection in combination with nucleos(t)ide analogue reverse transcriptase inhibitor (NrtI) therapy in adult patients without cirrhosis, receiving NrtI therapy for at least 6 months, who have suppressed HBV deoxyribonucleic acid (DNA), and with hepatitis B virus (HBV) surface antigen (HBsAg) levels ≤3000 IU/ml, as determined by an FDA-authorized test. GSK licensed bepirovirsen from Ionis and collaborated with them on its development.

Bepirovirsen is a first in class RNA-targeted medicine that offers unprecedented functional cure rates compared to current standard of care. The approval was granted under FDA priority review and Breakthrough Therapy Designation, recognizing significant improvement of bepirovirsen and nucleos(t)ide analogue therapy over existing standard of care.

"About 1.7 million people in the U.S are living with chronic hepatitis B, and yet treatment options have been historically limited and the vast majority of people living with the chronic infection require lifetime care without achieving meaningful functional cure," said Brett P. Monia, Ph.D., chief executive officer, Ionis. "We are pleased to see the FDA approval of Hibsago, which adds to a growing portfolio of transformative medicines discovered and developed by Ionis that address serious diseases, including many that previously had limited or no available treatment options. We believe Hibsago will bring new hope to people living with chronic hepatitis B, offering the potential to achieve unprecedented functional cure rates after a six-month treatment course."

The approval was supported by results from the Phase 3 B-Well trials showing functional cure rates of 19% in adults with ≤3000 IU/ml HBsAg, compared to current standard of care alone, which typically achieves less than 1% functional cure rate after one year of treatment. Functional cure occurs when HBV DNA and HBsAg are undetectable for at least 24 weeks after stopping all treatment, indicating the disease is controlled by the immune system without medication.