The U.S. Food and Drug Administration approved Hibsago (bepirovirsen) injection, marking the first time an antisense oligonucleotide has been authorized to treat chronic hepatitis B virus (HBV) infection. The drug is indicated for specific adults without cirrhosis who have been on existing antiviral therapy for at least six months, have suppressed viral levels, and show hepatitis B surface antigen (HBsAg) levels of 3,000 IU/mL or less.
New Approach to Viral Control
Chronic hepatitis B is a long-term liver infection that can lead to cirrhosis and liver cancer over time. Hibsago works by targeting the genetic instructions the virus uses to replicate itself and produce viral proteins. This mechanism helps reduce the amount of virus and HBsAg in the body.
Wendy Carter, DO, Acting Director of the Office of Infectious Diseases in the Center for Drug Evaluation and Research, stated that Hibsago provides a new treatment approach. She noted that it gives some patients the possibility of maintaining control of the virus after all chronic HBV treatment has ended. This approval represents an important advance for people living with this serious disease.
Clinical Trial Results and Eligibility
Researchers evaluated Hibsago in two clinical trials comparing it with a placebo. The treatment involves subcutaneous injections for up to 24 weeks. Patients continue their existing hepatitis B medicine for at least 24 weeks after their last Hibsago injection. Some patients may then stop their existing medicine if they meet specific health and lab test requirements.
Across the two trials, 24% of patients who received Hibsago met the requirements to stop their existing medicine, compared with none who received the placebo. Twenty-four weeks after stopping all hepatitis B treatment, 19% of patients who received Hibsago still had the virus under control. In these patients, HBsAg could not be detected in their blood.
To assist in selecting patients for treatment and monitoring throughout the course of therapy, the FDA also authorized the Roche Elecsys HBsAg II quant II RxDx assay as a companion diagnostic device. This test helps determine eligibility based on the FDA-approved drug labeling.
Safety Warnings and Side Effects
Hibsago carries a boxed warning for serious liver reactions and low platelet counts, which can increase the risk of potentially life-threatening bleeding. The drug also includes warnings for worsening kidney function and serious inflammatory adverse reactions like vasculitis. There are serious risks if the injection is not administered properly.
Patients need regular blood tests and follow-up with their healthcare provider before and during treatment to monitor these risks. The most common side effects, excluding laboratory abnormalities, are injection site reactions, fever, fatigue, and headache.
GSK plc received the approval for Hibsago. The FDA granted the drug Fast Track and Breakthrough Therapy designations as well as Priority Review status. The agency continues to protect public health by assuring the safety, effectiveness, and security of human drugs and medical devices.
Source: U.S. FDA
