GSK wins FDA approval for Hibsago in chronic hepatitis B

An option to end ongoing hepatitis B medication has opened for some adults after GSK plc LONGSK NYSEGSK won FDA approval for Hibsago on Tuesday. The decision permits a 24-week course of bepirovirsen alongside existing antivirals in adults without cirrhosis who meet specific laboratory criteria.

Patients must have received antiviral therapy for at least six months and have suppressed viral DNA. Hepatitis B surface antigen must be 3,000 international units per millilitre or less, as determined by an FDA-authorized test.

GSK is a large British medicines and vaccines company expanding its hepatology portfolio.

GSK's New York shares traded at US$50.21, below their US$50.63 previous close, at 10:48 a.m. EDT on Wednesday, according to NYSEGSK. A United States launch date and price could not be verified from the approval materials reviewed; GSK's next results are scheduled for Oct. 28.

Chronic hepatitis B is a long-term liver infection that can lead to cirrhosis and liver cancer. Hibsago targets the genetic instructions the virus uses to replicate and make proteins, helping reduce viral and surface-antigen levels.

Antiviral Treatment Continues After The Injections

The two Phase 3 B-Well trials were randomised, double-blind comparisons against placebo, with both groups continuing existing antiviral therapy. GSK's Oct. 20 approval release reported functional cure in 233 of 1,220 bepirovirsen recipients, or 19 per cent. None of the 614 placebo recipients achieved that endpoint.

Functional cure meant undetectable viral DNA and surface antigen for at least 24 weeks after all treatment ended. GSK said each study showed a statistically significant improvement, although its approval release did not provide a p value or confidence interval.

The FDA says patients continue existing antiviral medicine for at least 24 weeks after their final Hibsago injection. Only patients meeting subsequent health and laboratory requirements may then stop that medicine, so the injection course alone does not mark the end of treatment.

The October prescribing information calls for injections twice a week initially and weekly thereafter, with regular blood tests to monitor liver function and platelet counts. Hibsago carries boxed warnings for serious liver reactions and potentially life-threatening low platelet counts; the FDA also warns about kidney deterioration and inflammatory reactions.

"Hibsago provides a new treatment approach that gives some patients the possibility of maintaining control of the virus after all chronic HBV treatment has ended," Wendy Carter, acting director of the FDA's infectious diseases office, said.

Ionis Has A Royalty Interest In Sales

GSK's Oct. 20 release estimates that chronic hepatitis B affects about 1.7 million people in the United States. The approved population is narrower because eligibility depends on cirrhosis status, prior antiviral treatment and blood-test results.

GSK licensed the medicine from Ionis Pharmaceuticals, Inc. NASDAQIONS, whose April 28 release sets out royalties of 10 to 12 per cent on net sales. Ionis is also eligible for additional regulatory and sales milestone payments.

Gilead Sciences, Inc. NASDAQGILD reported second-quarter liver-disease sales of US$877 million on Aug. 4. Sales rose 10 per cent from the same period in 2025, with growth in chronic hepatitis B products among the drivers. That portfolio also includes medicines for other liver diseases, so its revenue is broader than the market Hibsago addresses.

The State Street Health Care Select Sector SPDR ETF NYSEARCAXLV traded at US$178.43, down 0.77 per cent, at 10:17 a.m. EDT on Wednesday.

GSK is scheduled to report third-quarter results on Oct. 28. The announcement is the next scheduled opportunity to clarify launch timing and how Hibsago fits its sales outlook.