The U.S. Food and Drug Administration on Tuesday approved Hibsago, a first-of-its-kind medicine that can put chronic hepatitis B into remission and let some patients stop treatment altogether, according to Reuters. The drug, chemically known as bepirovirsen, is the first antisense oligonucleotide therapy ever cleared by the agency for the liver infection.
Hibsago was developed by British drugmaker GSK, which licensed the compound from Ionis Pharmaceuticals. The approval covers adults without cirrhosis who have been on antiviral therapy for at least six months, have suppressed levels of the virus in their blood, and show hepatitis B surface antigen levels of 3,000 international units per milliliter or less, as confirmed by an FDA-authorized diagnostic test.
The decision rests on two Phase 3 trials, B-Well 1 and B-Well 2, which compared the drug against placebo in patients already taking standard antivirals. Across the trials, 24 percent of patients receiving Hibsago met the criteria to stop their existing antiviral medication, compared with none in the placebo groups. At 24 weeks after stopping all treatment, 19 percent — 233 of 1,220 treated participants — maintained undetectable virus levels and surface antigen, the marker of what doctors call a functional cure. Among patients whose starting antigen levels were 1,000 units or lower, the cure rate reached 26 percent.
The treatment is given as a six-month course, with patients able to self-administer injections after the first dose. It carries a boxed warning — the FDA's most serious safety label — for serious liver reactions and low platelet counts that can increase the risk of life-threatening bleeding, and patients need regular blood tests and monitoring. GSK expects peak annual sales above 2 billion pounds and says the drug is already approved in Japan and under review in China and Europe. More than 250 million people worldwide live with chronic hepatitis B, and today's standard drugs help only 1 to 4 percent of patients clear the virus long-term, MedPage Today reports.