GSK's Bepirovirsen Hits 19% Functional Cure Rate in Hepatitis B Trials, Redefining Treatment Landscape — Ionis Pharmaceuticals, Inc.

Event summary

GSK's bepirovirsen achieved a 19% functional cure rate in Phase 3 trials for chronic hepatitis B, surpassing the <1% rate of current standard treatments.
In a key subset of patients with baseline HBsAg ≤1000 IU/mL, the functional cure rate reached 26%, representing 45% of diagnosed CHB cases globally.
Bepirovirsen is under priority review by the FDA with Breakthrough and Fast Track Designation, with regulatory decisions expected in Q3 2026.
Ionis, which licensed bepirovirsen to GSK in 2019, stands to receive tiered royalties of 10-12% on net sales and additional milestone payments.

The big picture

GSK's bepirovirsen represents a potential paradigm shift in the treatment of chronic hepatitis B, a disease affecting over 240 million people globally. The drug's ability to achieve functional cures in a significant proportion of patients could disrupt the current market dominated by lifelong antiviral therapies. Ionis, as the licensor, stands to benefit from milestone payments and royalties, highlighting the strategic value of its antisense oligonucleotide technology platform.

What we're watching

Regulatory Approval: Whether the FDA and other global regulators will approve bepirovirsen by Q3 2026, given its unprecedented functional cure rates.
Market Penetration: The pace at which bepirovirsen can capture market share from existing lifelong antiviral therapies for chronic hepatitis B.
Commercialization Strategy: How GSK plans to position bepirovirsen in markets with high hepatitis B prevalence, such as China, where 75 million people are affected.