FDA approves GSK's hepatitis B drug from Ionis, triggering royalties of 10% to 12% for Ionis

Ionis Pharmaceuticals has a new royalty stream on the way after the Food and Drug Administration approved a hepatitis B treatment that Ionis discovered and licensed to GSK.

The FDA approved Hibsago, known as bepirovirsen, for chronic hepatitis B virus infection in combination with standard nucleos(t)ide analogue therapy, Ionis said in an 8-K filed Wednesday, citing GSK's Oct. 20 announcement.

The approval covers adults without cirrhosis who have been on that therapy for at least six months, have suppressed viral DNA and have hepatitis B surface antigen levels of 3,000 IU/ml or less, as determined by an FDA-authorized test.

What Ionis gets

GSK licensed bepirovirsen from Ionis in 2019. Ionis has already received an upfront payment, a license fee and development and regulatory milestone payments, and it is eligible for more regulatory and sales milestones plus tiered royalties of 10% to 12% on net sales, according to the filing.

The data

The approval was supported by Phase 3 B-Well trials showing functional cure rates of 19% in adults with surface antigen levels of 3,000 IU/ml or less, compared with standard of care alone, which typically achieves a functional cure rate of less than 1% after one year, the release said. Functional cure means viral DNA and surface antigen stay undetectable for at least 24 weeks after stopping all treatment.

The FDA granted the approval under priority review and Breakthrough Therapy designation. Treatment runs six months, with an option for at-home administration after the first dose.

"About 1.7 million people in the U.S are living with chronic hepatitis B," Ionis CEO Brett Monia said in the release.

Sources

1. Ionis Pharmaceuticals, Inc., Form 8-K (Items 7.01, 8.01) with Exhibit 99.1 press release dated Oct. 20, 2026, filed Oct. 21, 2026, accession 0001140361-26-040388

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