FDA approves Hibsago, first antisense drug for chronic hepatitis B, with boxed warning
In two placebo-controlled trials, 24% of patients on the drug met criteria to stop all hepatitis B therapy, and 19% still had the virus under control 24 weeks later, the FDA said.
Key takeaways
- The FDA approved Hibsago (bepirovirsen) injection on October 20, 2026, for chronic hepatitis B in certain adults without cirrhosis, used with existing antiviral therapy.
- The FDA calls it the first approved antisense oligonucleotide for chronic hepatitis B; the approval went to GSK plc.
- Across two placebo-controlled trials, 24% of Hibsago patients met the requirements to stop their existing hepatitis B medicine, compared with none on placebo.
- Hibsago carries a boxed warning for serious liver reactions and low platelet counts, plus warnings for worsening kidney function and inflammatory reactions such as vasculitis.
- For crews: patients on Hibsago receive it as an under-the-skin injection for up to 24 weeks and need regular blood tests during treatment, per the FDA release.
The U.S. Food and Drug Administration approved Hibsago (bepirovirsen) injection on October 20, 2026, for chronic hepatitis B virus infection in certain adults without cirrhosis, according to an FDA news release issued that day [1]. The drug is given together with existing antiviral therapy. The FDA describes Hibsago as the first antisense oligonucleotide it has approved for chronic hepatitis B [1].
The approval was granted to GSK plc [1]. The same day, the FDA authorized a Roche blood test, the Elecsys HBsAg II quant II RxDx assay, as a companion diagnostic. The release says the test is meant to help select patients for treatment under the drug's labeling and to help monitor them while they are treated [1].
Wendy Carter, DO, Acting Director of the Office of Infectious Diseases in the Center for Drug Evaluation and Research, said in the release that Hibsago "gives some patients the possibility of maintaining control of the virus after all chronic HBV treatment has ended" [1].
What the records show
The approval is narrow. According to the FDA, Hibsago is for adults without cirrhosis who have taken hepatitis B antiviral therapy for at least six months, who have suppressed levels of the virus in their blood, and whose hepatitis B surface antigen (HBsAg) level is 3,000 IU/mL or less on an FDA-authorized test [1].
The FDA says the drug works by targeting the genetic instructions the virus uses to copy itself and to make viral proteins. The agency says this lowers the amount of virus and of HBsAg in the body [1].
Hibsago is injected under the skin for up to 24 weeks, per the release. Patients keep taking their existing hepatitis B medicine during treatment and for at least 24 weeks after the last injection. After that, the FDA says, some patients may stop the existing medicine if they meet "certain health and lab test requirements" [1].
The FDA based the approval on two clinical trials that compared Hibsago with placebo [1]. The release reports the following results:
| Outcome reported by the FDA | Hibsago | Placebo |
|---|---|---|
| Met requirements to stop existing hepatitis B medicine | 24% | None |
| Virus under control and HBsAg undetectable 24 weeks after stopping all treatment | 19% | Not reported |
Hibsago carries a boxed warning for serious liver reactions and for low platelet counts, which the FDA says can raise the risk of potentially life-threatening bleeding [1]. The label also warns of worsening kidney function, serious inflammatory adverse reactions such as vasculitis, and serious risks if the injection is given improperly. The FDA says patients need regular blood tests and follow-up with their provider before and during treatment [1].
The most common side effects, apart from laboratory abnormalities, were injection site reactions, fever, fatigue and headache, according to the release [1]. The FDA granted the application Fast Track designation and Priority Review, among other expedited designations [1].
Why it matters for clinicians
Chronic hepatitis B is a long-term liver infection, and the FDA says it can progress to cirrhosis and raise the risk of liver cancer [1]. Until now, the release says, treatment for many patients has meant years of antiviral medication to keep the virus suppressed. Hibsago is the first approved drug the FDA describes as offering some patients a chance to stop all hepatitis B therapy [1].
The safety profile is relevant to anyone who assesses these patients in acute settings. The boxed warning covers serious liver reactions and low platelet counts with a bleeding risk [1]. The label also flags kidney function and vasculitis [1]. Patients on the drug will be receiving repeated injections over a period of up to 24 weeks while still taking their prior antiviral, and will be undergoing regular laboratory monitoring [1]. EMS clinicians follow local protocols and medical direction.
The companion diagnostic matters for the treatment pathway. The FDA says the Roche assay is authorized both to help select patients and to assist in monitoring them through the course of treatment [1].
What the records do not tell us
The FDA release does not give the number of patients enrolled in the two trials, the names of the trials, their duration, or where they were run [1]. It does not say how often injections are given within the 24-week course, or what dose is used.
The release does not define the "certain health and lab test requirements" a patient must meet before stopping existing therapy [1]. It does not explain what happened to patients who met the stopping criteria but did not keep the virus under control 24 weeks later. It does not report rates for any adverse reaction, including how many trial patients had serious liver reactions or low platelets.
The records do not include data for people with cirrhosis, for children, or for adults with HBsAg above 3,000 IU/mL [1]. They do not state a price, an availability date, or whether use of the Roche companion test is required rather than permitted. The release contains no statement from GSK or Roche. The full prescribing information is not part of the records reviewed here.
Questions readers ask
What is Hibsago and what did the FDA approve it for?
Hibsago (bepirovirsen) is an antisense oligonucleotide injection made by GSK plc. On October 20, 2026, the FDA approved it, in combination with existing antiviral therapy, to treat chronic hepatitis B virus infection in certain adults without cirrhosis.
Who is eligible for Hibsago under the FDA approval?
According to the FDA, Hibsago is approved for adults without cirrhosis who have been on hepatitis B antiviral therapy for at least six months, have suppressed levels of HBV in their blood, and have HBsAg levels of 3,000 IU/mL or less as measured by an FDA-authorized test.
How well did Hibsago work in clinical trials?
Across two placebo-controlled trials, the FDA reported that 24% of patients who received Hibsago met the requirements to stop their existing hepatitis B medicine, compared with none on placebo. Twenty-four weeks after stopping all treatment, 19% of Hibsago patients still had the virus under control with undetectable HBsAg.
What are the warnings and side effects of Hibsago?
Hibsago has a boxed warning for serious liver reactions and low platelet counts, which can increase the risk of potentially life-threatening bleeding. The FDA also lists warnings for worsening kidney function, serious inflammatory reactions such as vasculitis, and risks from improper injection. The most common side effects are injection site reactions, fever, fatigue and headache.
Sources
- FDA News Release: FDA Approves First-of-Its-Kind Chronic Hepatitis B Treatment (October 20, 2026) — fda.gov (2026-10-20). fda.gov/news-events/press-announcements/fda-approves-first-its-kind-ch
This is news, not medical advice. EMS clinicians: follow your local protocols and medical direction.
