Sanofi's cholesterol drug reports positive test results PARIS (Reuters) - An experimental cholesterol treatment being jointly developed by Regeneron and Sanofi has shown it can lower bad cholesterol levels in difficult-to-treat patients, according to data from a mid-stage study published on Saturday. The treatment, a monoclonal antibody that works by blocking a protein called PCSK9 which preserves high bad cholesterol levels in the bloodstream, is a component of a new type of drug that could become effective in preventing heart attack and stroke. The trial tested 77 patients with an inherited condition that causes high cholesterol levels who did not respond to standard cholesterol-lowering therapy with statins. After 12 weeks, patients taking REGN727 saw their cholesterol levels reduced by between 28.9 percent and 67.9 percent depending on their dosing regime, compared with 10.7 percent among those taking a dummy treatment. The results from the study were published online in medical journal The Lancet and also presented at the European Atherosclerosis Society Congress in Milan, Italy. Sanofi and Regeneron said that they plan to start a late-stage trial for REGN727 in June. Reporting by Elena Berton; editing by Keiron Henderson