CAMBRIDGE, Mass., Dec. 2, 2013 (GLOBE NEWSWIRE) -- Idenix Pharmaceuticals, Inc. (Nasdaq:IDIX), a biopharmaceutical company engaged in the discovery and development of drugs for the treatment of human viral diseases, today announced the initiation of patient enrollment in the phase II HELIX-2 clinical trial evaluating an all-oral, direct-acting antiviral (DAA) HCV combination regimen of samatasvir, Idenix's once-daily pan-genotypic NS5A inhibitor, simeprevir, a once-daily NS3/4A protease inhibitor jointly developed by Janssen R&D Ireland and Medivir AB, and TMC647055, a once-daily NS5B non-nucleoside polymerase inhibitor boosted with low-dose ritonavir developed by Janssen. The HELIX-2 trial is a 12-week, randomized, open-label study evaluating the efficacy, safety and tolerability of samatasvir, simeprevir, and TMC647055. The trial will evaluate genotype 1 HCV-infected patients who are either treatment-naïve or who have relapsed after prior treatment with interferon and ribavirin. Patients will receive 50 mg samatasvir, 75 mg of simeprevir and 450 mg of TMC647055/ritonavir (30 mg), each once daily for 12 weeks, with or without ribavirin. The HELIX-2 trial is the second study in HCV-infected patients to commence under a non-exclusive collaboration agreement signed with Janssen in January 2013. The HELIX-1 trial of samatasvir in combination with simeprevir was initiated in May 2013 and is ongoing. "We are pleased with the continuing progress of our clinical program for samatasvir, which will provide additional important information on the use of this promising compound as part of all-oral HCV combination regimens," said Doug Mayers, M.D., Idenix's Chief Medical Officer. "With the advancement of the samatasvir program as well as that of our novel nucleotide prodrug inhibitor, IDX21437, we anticipate initiating the evaluation of our own HCV combination regimen in 2014." ABOUT THE IDENIX/JANSSEN COLLABORATION In January 2013, Idenix entered into a non-exclusive collaboration with Janssen Pharmaceuticals for the clinical development of all-oral direct-acting antiviral (DAA) HCV combination therapies. The collaboration is evaluating combinations including samatasvir, simeprevir, and TMC647055. The HELIX-1 and HELIX-2 clinical trials are being conducted by Idenix. Both Idenix and Janssen retain all rights to their respective compounds under the agreement.