FDA Approves GSK’s Hibsago, a First-of-Its-Kind Hepatitis B Shot That Could Let Some Patients Stop Treatment

The Food and Drug Administration on Tuesday approved Hibsago, a new injectable hepatitis B treatment from GSK that gives some patients something today’s drugs almost never do: a real chance to stop treatment and keep the virus in check.

Hibsago, known chemically as bepirovirsen, is the first antisense drug the FDA has approved for chronic hepatitis B. It is not a replacement for the antiviral pills patients already take. It is added on top of them for up to 24 weeks, with the goal of knocking the virus down far enough that some people can eventually come off all hepatitis B medicine.

“For many people living with chronic hepatitis B, treatment can mean taking antiviral medication for years to keep the virus suppressed,” said Dr. Wendy Carter, acting director of the Office of Infectious Diseases in the FDA’s drug center. “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.”

What is Hibsago and how does it work?

Hibsago is an antisense oligonucleotide, a short strand of genetic material designed to latch onto the instructions the virus uses to copy itself and make its proteins. By breaking that process, the drug lowers the amount of virus in the body and the level of hepatitis B surface antigen, or HBsAg, a protein that signals an ongoing infection.

That second target is the important one. The pills most patients take today, known as nucleoside or nucleotide analogues, are good at suppressing the virus but rarely clear surface antigen. That is why many people stay on them for life. Standard treatment helps only about 1% to 4% of patients reach what doctors call a functional cure, Reuters reported.

GSK licensed the drug from Ionis Pharmaceuticals, which developed it. The FDA gave it Fast Track and Breakthrough Therapy designations and a Priority Review.

Who can get Hibsago?

The approval is narrow. According to the FDA’s announcement, Hibsago is for adults with chronic hepatitis B who:

• do not have cirrhosis of the liver,
• have been on hepatitis B antiviral therapy for at least six months,
• have suppressed levels of the virus in their blood, and
• have HBsAg levels of 3,000 IU/mL or less, measured with an FDA-authorized test.

Alongside the drug, the FDA authorized a Roche blood test, the Elecsys HBsAg II quant II RxDx assay, as a companion diagnostic. Doctors will use it to decide who qualifies and to track patients during treatment.

How well did Hibsago work in clinical trials?

GSK tested the drug in two placebo-controlled phase 3 trials, called B-Well 1 and B-Well 2. Patients received Hibsago as an injection under the skin for up to 24 weeks while staying on their usual antiviral, then kept taking that antiviral for at least another 24 weeks.

Across both studies, 24% of patients on Hibsago met the requirements to stop their existing hepatitis B medicine. None of the placebo patients did. Twenty-four weeks after stopping all hepatitis B treatment, 19% of Hibsago patients still had the virus under control and no detectable surface antigen in their blood.

That is roughly one in five patients reaching a result that has been rare with today’s drugs. Most did not.

What are the risks and side effects?

Hibsago carries a boxed warning, the FDA’s strongest, for serious liver reactions and for low platelet counts, which can raise the risk of life-threatening bleeding. The label also warns about worsening kidney function, serious inflammatory reactions such as vasculitis, and risks if the injection is not given properly.

Patients will need regular blood tests and follow-up visits before and during treatment. The most common side effects, aside from lab changes, were injection-site reactions, fever, fatigue and headache.

How many Americans have hepatitis B?

The Centers for Disease Control and Prevention estimates that about 640,000 adults in the United States are living with chronic hepatitis B. Patient groups such as the Hepatitis B Foundation put the number much higher, at up to 2.4 million, because many people do not know they are infected. Worldwide, more than 250 million people have the chronic infection.

Left untreated, hepatitis B can scar the liver, cause cirrhosis and raise the risk of liver cancer. The virus spreads through blood and other body fluids, and a vaccine prevents it. We covered recent changes to that schedule in our report on the CDC’s childhood immunization overhaul.

How much will Hibsago cost, and when can patients get it?

GSK has not yet said what Hibsago will cost in the United States or exactly when it will reach pharmacies and clinics. The company did not immediately respond to a Reuters question about U.S. pricing and availability.

GSK expects the drug to bring in more than $2.6 billion a year at its peak, according to Reuters, and Japan already approved it in August. Reviews are underway in Europe and China.

Price will shape who actually gets it. New brand-name drugs routinely launch at six-figure annual prices, a pattern we reported on this week in our story on new drug launch prices. Because Hibsago is a limited course rather than a lifelong prescription, insurers will be weighing its cost against years of antiviral pills and liver care it might replace.

Key takeaways

• The FDA approved GSK’s Hibsago (bepirovirsen) on Oct. 20, 2026, the first antisense treatment for chronic hepatitis B.
• It is added to existing antiviral pills for up to 24 weeks, for adults without cirrhosis whose virus is already suppressed and whose HBsAg is 3,000 IU/mL or lower.
• In two phase 3 trials, 19% of patients kept the virus under control six months after stopping all hepatitis B treatment.
• The drug has a boxed warning for serious liver reactions and low platelets. U.S. price and launch timing have not been announced.

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