The US Food and Drug Administration (FDA) on Tuesday, 21 October 2026, approved Hibsago (bepirovirsen), a first-of-its-kind injectable treatment for chronic hepatitis B virus (HBV) infection, opening the possibility for certain patients to stop all antiviral medication while maintaining viral control. Developed by GSK plc, Hibsago is the first FDA-approved antisense oligonucleotide for hepatitis B — a significant milestone in a disease area where patients have historically faced decades of daily medication.

What Hibsago Is and How It Works

Hibsago belongs to a class of medicines called antisense oligonucleotides, which are designed to interfere with the genetic instructions that allow the hepatitis B virus to reproduce and produce viral proteins. Unlike conventional antivirals that suppress the virus only while being taken, this mechanism targets the virus's ability to sustain itself at a molecular level.

The approval applies to adults with chronic hepatitis B without cirrhosis who have already undergone antiviral therapy for at least six months and have achieved suppressed HBV levels in the blood. Patients must also have hepatitis B surface antigen (HBsAg) levels of 3,000 international units per millilitre or less, confirmed via an FDA-authorised diagnostic test — a companion test developed by Roche and simultaneously authorised by the agency.

What the Clinical Trials Found

The FDA evaluated Hibsago across two clinical trials comparing the drug against a placebo. Patients received injections under the skin for up to 24 weeks while continuing existing antiviral medication, followed by at least another 24 weeks on standard antivirals after the final Hibsago dose.

Across both trials, 24 per cent of Hibsago recipients met the criteria required to discontinue their existing antiviral medication, compared with none in the placebo groups. Among those who stopped all hepatitis B treatment, 19 per cent continued to demonstrate viral control at the 24-week post-treatment mark, with hepatitis B surface antigen no longer detectable in their blood.

The findings indicate that a meaningful proportion of eligible patients may achieve sustained control without ongoing therapy, though the majority of trial participants did not reach this outcome — a nuance the FDA underscored in its assessment.

Safety Risks and Monitoring Requirements

The FDA emphasised that Hibsago carries significant safety risks. Its prescribing information includes a boxed warning — the agency's most serious advisory — covering serious liver reactions and reduced platelet counts, which can raise the risk of potentially life-threatening bleeding. Additional warnings concern worsening kidney function, serious inflammatory reactions including vasculitis, and complications from improper administration.

Patients on Hibsago will require regular blood tests and close medical monitoring before and throughout the course of treatment. The most commonly reported side effects, beyond laboratory abnormalities, included injection-site reactions, fever, fatigue, and headache.

Regulatory Designations and Significance

Hibsago received Fast Track, Breakthrough Therapy, and Priority Review designations from the FDA, reflecting the agency's view that the drug addresses a significant unmet medical need. Wendy Carter, acting director of the FDA's Office of Infectious Diseases, described the approval as 'an important advance for people living with this serious disease.'

'For many people living with chronic hepatitis B, treatment can mean taking antiviral medication for years to keep the virus suppressed,' Carter said. '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 This Means for India and Asia

Chronic hepatitis B remains a major public health burden across Asia, including India, where millions live with the infection and face elevated long-term risks of cirrhosis and liver cancer. The FDA approval covers the United States; the agency's announcement did not specify a timeline for commercial availability in India or other markets. Regulatory submissions to bodies such as India's Central Drugs Standard Control Organisation (CDSCO) would be a separate process. Access, pricing, and inclusion in public health programmes will be critical factors determining how broadly this advance reaches patients in the region.