Merck , known as MSD outside the United States and Canada, today announced the presentation of interim data from the C-SWIFT study exploring the potential of a candidate triple-therapy regimen consisting of the fixed-dose combination of grazoprevir/elbasvir , the company's investigational NS3/4A protease inhibitor and NS5A inhibitor, in combination with sofosbuvir, a nucleotide inhibitor for the treatment of chronic hepatitis C virus infection.