Ionis partner GSK gets FDA approval for hepatitis B treatment Hibsago
The FDA approved Hibsago (bepirovirsen), developed by GSK under a 2019 license from Ionis, for chronic hepatitis B in adults without cirrhosis who have suppressed HBV DNA and HBsAg levels of 3,000 IU/ml or less. Ionis has received an upfront payment, license fee and development and regulatory milestone payments, and is eligible for additional milestones and tiered royalties of 10-12% on net sales.
Key points
- Phase 3 B-Well trials showed a 19% functional cure rate (233 of 1,220) versus 0 of 614 in the placebo group, in adults with HBsAg of 3,000 IU/ml or less
- Current standard of care alone typically achieves less than 1% functional cure after one year of treatment, according to the filing
- The approval followed FDA priority review and Breakthrough Therapy Designation; the filing states about 1.7 million people in the U.S. have chronic hepatitis B
- The label includes boxed warnings for on-treatment hepatic flares and thrombocytopenia
The filing
Written by AI on Nov 9, 2026, 8:29 AM ET, from this filing only. Written later: this filing was briefed after the fact, when past filings were added to the site, so the brief may be read with hindsight; the filing itself is the record of what was known on October 21, 2026.
Briefs are written by AI from the filing text and can contain mistakes — open the filing before acting on anything. Impact (1-5) and tone are the AI's reading of the filing for shareholders, not a price forecast. Not investment advice.