FDA declines to approve Bristol-Myers hepatitis drug Wed Nov 26, 2014 1:06pm EST (Reuters) - Bristol-Myers Squibb Co on Wednesday said U.S. regulators had declined to approve the use of its experimental treatment for hepatitis C, daclatasvir, in combination with other antiviral drugs. Bristol-Myers said it had initially sought permission from the U.S. Food and Drug Administration to market the drug, a so-called NS5A inhibitor, in combination with asunaprevir, one of the New York-based company's experimental medicines. But Bristol-Myers abandoned its U.S. marketing application for asunaprevir in October because of potential competition from more potent drugs, leaving the FDA without data to gauge the effectiveness of daclatasvir as part of a combination regimen. Bristol-Myers said the FDA has asked it for data involving use of daclatasvir with other drugs, and that the company is in discussions with the agency about the scope of the required information. Most notably, it is testing daclatasvir in combination with Gilead Sciences Inc's Sovaldi, a blockbuster treatment that is used on its own or as a component of a combination treatment called Harvoni that was recently introduced by Gilead and is expected to quickly become the market leader. Bristol-Myers' combination of daclatasvir and asunaprevir, however, was approved in July for use in Japan, which it long considered a prime market for the treatment. One strain of the hepatitis C virus, Genotype 1b, is prevalent in Japan, where intolerance to interferon, an older medicine, is particularly high. In late-stage clinical trials, the combination treatment cured about 85 percent of patients with 24 weeks of therapy. The combinations being developed by rival drugmakers have demonstrated cure rates well in excess of 90 percent with just 12 weeks of therapy, and they are pursuing even shorter treatment durations. Bristol-Myers, meanwhile, is studying a three-drug regimen that, based on earlier studies, is expected to cure more people in 12 weeks and would compete more favorably with rival treatments. The U.S. marketing application for the company's three-drug combination is expected to be filed next year. Shares of Bristol-Myers were little changed in afternoon trading on Wednesday. Reporting by Ransdell Pierson; Editing by Paul Simao