The Food and Drug Administration has approved Hibsago (bepirovirsen) injection, in combination with existing antiviral therapy, to treat chronic hepatitis B in certain adults without cirrhosis. Patients must have taken hepatitis B antiviral therapy for at least six months, have suppressed levels of the virus in their blood, and have hepatitis B surface antigen levels of 3,000 IU/mL or less on an FDA authorised test. The agency called Hibsago the first FDA approved antisense oligonucleotide to treat chronic hepatitis B: it targets the genetic instructions the virus uses to make copies of itself and its proteins. The approval was granted to GSK plc, and the FDA also authorised a Roche test, the Elecsys HBsAg II quant II assay, as a companion diagnostic to help select and monitor patients. The drug had Fast Track and Breakthrough Therapy designations and Priority Review.
In two trials against placebo, Hibsago was injected under the skin for up to 24 weeks alongside patients’ existing medicine, which they continued for at least 24 weeks after the last injection. Across the trials, 24 percent of patients who received Hibsago met the requirements to stop their existing medicine, compared with none on placebo, and 24 weeks after stopping all hepatitis B treatment, 19 percent of Hibsago patients still had the virus under control with surface antigen undetectable in their blood. The product carries a boxed warning for serious liver reactions and low platelet counts, and its most common side effects, excluding laboratory abnormalities, were injection site reactions, fever, fatigue and headache.