GSK said its experimental chronic hepatitis B drug helped nearly one in five patients achieve a functional cure in late-stage studies, raising hopes ‌for a finite ⁠treatment ⁠course as an alternative to lifelong antiviral pills. The British drugmaker presented detailed data from two studies of bepirovirsen on Thursday at a medical conference. The drug is central to GSK's plans to achieve more than £40 billion ($54 billion) in annual revenue by 2031. The company expects peak annual sales of more than £2 billion for the drug. GSK said six months of treatment with bepirovirsen helped 19% of patients ⁠who started ‌with surface antigen levels of 3,000 international units per millilitre (IU/ml) or below achieve a functional cure. That means patients were off treatment ⁠for at least six months and had both hepatitis B virus DNA and surface antigen below detectable levels. The response rate rose to 26% among patients with surface antigen levels of 1,000 IU/ml or below. Analysts had estimated a 15% to 20% response rate would be significant and could support broad adoption. More than 250 million people globally live with chronic hepatitis B, and current standard-of-care treatments help only 1% to 4% of ‌patients clear the virus for a sustained period. Nucleotide analogues, a widely used class of therapies, are often taken for life and suppress the virus but rarely ⁠eliminate it. "To have six months of injections to achieve functional cure of this magnitude ... is, to me, a great advance in the management of my patients," said Dr. Seng Gee Lim, lead investigator of the studies. He added the drug was generally well tolerated, with most side effects limited to mild injection-site reactions. GSK has sought regulatory approval for bepirovirsen in the U.S., Japan, China and Europe. A decision from the U.S. regulator is expected by October 26.