Some adults with chronic hepatitis B now have a treatment designed to end. On 20 October 2026, the U.S. Food and Drug Administration (FDA) approved Hibsago (bepirovirsen), developed by GSK, as the first antisense oligonucleotide authorised for chronic hepatitis B virus infection. Standard antivirals suppress the virus for as long as they are taken, and most patients stay on them indefinitely. In the trials behind this approval, roughly one in five treated patients kept the virus under control after every hepatitis B medicine was stopped, an outcome the field calls a functional cure. The FDA's acting director of the Office of Infectious Diseases, Wendy Carter, said the approval gives some patients “the possibility of maintaining control of the virus after all chronic HBV treatment has ended.”
What the FDA Approved
The approval is narrow and test-driven. Hibsago is used in combination with a nucleos(t)ide analogue reverse transcriptase inhibitor in adults who do not have cirrhosis, have already received that antiviral therapy for at least six months, have suppressed HBV DNA, and have hepatitis B surface antigen (HBsAg) levels of 3,000 IU/mL or lower, measured with an FDA-authorised test. Patients receive a weekly injection under the skin for up to 24 weeks while continuing their existing antiviral, and they stay on that antiviral for at least another 24 weeks after the final injection. Only then, and only if clinical and laboratory criteria are met, may the background therapy be stopped. Bepirovirsen works by targeting the genetic instructions the virus uses to copy itself and produce viral proteins, lowering both virus levels and HBsAg so the immune system can hold the infection down unaided. GSK licensed the drug from Ionis and developed it jointly. The FDA granted it Fast Track and Breakthrough Therapy designations and Priority Review, and the approval was granted to GSK plc. The agency also authorised the Roche Elecsys HBsAg II quant II RxDx assay as a companion diagnostic to help select patients and monitor them during treatment.
What the B-Well Trials Showed
The decision rests on B-Well 1 and B-Well 2, two global, randomised, double-blind, placebo-controlled phase 3 trials run in 29 countries in adults on stable antiviral therapy. The FDA's summary of the results is the cleanest version: 24% of patients who received Hibsago met the requirements to stop their existing medicine, compared with none who received placebo, and 24 weeks after all hepatitis B treatment had stopped, 19% of the Hibsago group still had the virus under control with HBsAg no longer detectable. GSK's pooled figures line up with that summary: a 19% functional cure rate overall (233 of 1,220 patients, versus 0 of 614 on placebo), rising to 26% (200 of 768, versus 0 of 393) among patients whose starting HBsAg was 1,000 IU/mL or lower, a group GSK estimates is about 45% of diagnosed cases. By week 72, HBsAg had fallen to 100 IU/mL or below in 49% of treated patients overall and 62% of that lower-antigen subgroup. For context, GSK states that current standard therapy alone produces functional cure in under 1% of patients after a year of treatment. Functional cure does not mean the virus is eradicated. It means HBV DNA and HBsAg stay undetectable for at least 24 weeks off all treatment, under immune control.
Safety Warnings and Monitoring
The label carries a boxed warning, and it shapes how clinics must run the pathway. The FDA highlights serious liver reactions and low platelet counts, the latter raising the risk of potentially life-threatening bleeding. GSK's prescribing information describes on-treatment hepatic flares, with sharp rises in the liver enzyme ALT mostly in the first 12 weeks, and sudden drops in platelet count. Hibsago is contraindicated in patients with cirrhosis or acute hepatic impairment and in those starting with a platelet count below 100 x 10⁹/L. Further warnings cover worsening kidney function, which was generally reversible after treatment stopped, and serious inflammatory or immune reactions including vasculitis. The most common side effects, excluding laboratory changes, were injection site reactions, fever, fatigue and headache. The practical consequence is a monitoring schedule: liver tests, platelet counts and kidney function before and repeatedly during treatment, plus at least a year of follow-up monitoring if the background antiviral is later stopped, because severe hepatitis flares can follow withdrawal of anti-HBV therapy.
What This Means for Hepatitis B Care
For hepatology, gastroenterology and infectious-disease practices, the work created by this approval is identification and follow-through rather than volume. Eligibility depends on a quantitative HBsAg result, so practices need that test ordered, resulted and visible in the chart for every long-term antiviral patient who might qualify, and a recall process for patients whose antigen level sits in the eligible range. The 24-week injection course, the frequent blood monitoring and the year of post-stop surveillance all have to be scheduled, reminded and tracked reliably. That is exactly the kind of longitudinal coordination that patient-facing systems are meant to support, from test-result delivery to appointment reminders (see https://medclinicx.com/solutions/ai-patient-portal). Counselling matters just as much: four in five treated patients did not reach functional cure in the trials, so expectations must be set honestly before the first injection, and patients with HIV or hepatitis D co-infection need specialist review because stopping background therapy carries added risks for them. GSK cites more than 240 million people living with chronic hepatitis B worldwide and about 1.1 million deaths a year, which is why even a one-in-five success rate is a material change. This article is general information about a regulatory decision, not medical advice for any individual patient.
Analysis: A Finite Course, Judged on Who Can Stop Safely
Analysis (MedClinicX): The significance of this approval is structural. Hepatitis B care has been organised around indefinite suppression. Hibsago introduces a defined course with a defined stopping question at the end of it, and a companion diagnostic that decides who is even a candidate. That pattern, biomarker-gated, time-limited, monitoring-heavy, is where specialty drug pathways are heading, and it rewards clinics whose recall, laboratory and follow-up workflows are already disciplined. The open questions are durability and reach: the headline result is measured 24 weeks after stopping, longer follow-up will show how many patients stay controlled over years, and the eligible population is limited to non-cirrhotic patients with already-suppressed virus and relatively low antigen levels. Payers will also test the economics of a six-month course against cheap generic antivirals taken for life. None of that diminishes the approval itself. It defines what early adopters should measure and report.
Sources and References
- U.S. Food and Drug Administration, FDA Approves First-of-Its-Kind Chronic Hepatitis B Treatment, 20 October 2026: https://www.fda.gov/news-events/press-announcements/fda-approves-first-its-kind-chronic-hepatitis-b-treatment
- GSK (via Business Wire), Hibsago (bepirovirsen) Approved in the US for the Treatment of Chronic Hepatitis B (CHB), 20 October 2026: https://www.businesswire.com/news/home/20261020329825/en/Hibsago-bepirovirsen-Approved-in-the-US-for-the-Treatment-of-Chronic-Hepatitis-B-CHB
- Reuters, US FDA approves GSK's hepatitis B drug, offering patients chance to stop long-term treatment, 20 October 2026: https://ktwb.com/2026/10/20/us-fda-approves-gsks-hepatitis-b-drug-offering-patients-chance-to-stop-long-term-treatment/
- HCPLive, FDA Approves Bepirovirsen for Chronic Hepatitis B, 20 October 2026: https://www.hcplive.com/view/fda-approves-bepirovirsen-for-chronic-hepatitis-b
Reporting based on the sources above, accessed 21 October 2026. The FDA announcement and the GSK announcement were read directly in full. MedClinicX did not conduct original reporting or interviews for this article. Corrections: contact us via https://medclinicx.com/contact