WASHINGTON (AP) — A first-of-its-kind drug for hepatitis B is letting some patients stop treatment without showing signs of the dangerous liver virus, what’s called a “functional cure,” researchers reported Thursday.In two international studies, about 1 in 5 patients given the experimental drug saw their virus reduced to levels low enough for the immune system to keep in check.“We have not had a treatment which has come to this level of cure,” Dr. Seng Gee Lim of the National University Health System of Singapore, who helped lead the GSK-funded studies, told reporters before presenting the findings at a scientific meeting in Barcelona, Spain.The data also was published Thursday in the New England Journal of Medicine.Chronic hepatitis B can cause liver cancer or liver failure, and kills about 1.1 million people around the world each year. Improvements to today’s lifelong therapy, which can be hard to stick with or to access in some countries, have been sought for decades.

The new findings “represent a major step,” Dr. Anna Lok, a hepatitis expert at the University of Michigan who wasn’t involved in the research, wrote in the journal. But she cautioned that more study is needed to see how long that remission-like state lasts.