CAMBRIDGE, Mass., May 30, 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 the phase II HELIX-1 clinical trial evaluating an all-oral, direct-acting antiviral (DAA) HCV combination regimen of samatasvir (IDX719), Idenix's once-daily pan-genotypic NS5A inhibitor, and simeprevir (TMC435), a once-daily protease inhibitor jointly developed by Janssen R&D Ireland and Medivir AB. The HELIX-1 trial is a 12-week, randomized, double-blind, parallel group study evaluating the safety and tolerability of samatasvir and simeprevir in addition to antiviral activity endpoints, with a target enrollment of 90 treatment-naïve, non-cirrhotic, genotype 1b or 4 HCV-infected patients. Patients will be randomized equally across three treatment arms, receiving either 50, 100, or 150 mg samatasvir once-daily for 12 weeks in combination with simeprevir plus ribavirin. The HELIX-1 trial is the first study in HCV-infected patients to commence under a non-exclusive collaboration agreement signed with Janssen in January 2013. A second trial (HELIX-2) of samatasvir, simeprevir and TMC647055, a once-daily non-nucleoside polymerase inhibitor boosted with low-dose ritonavir being developed by Janssen, is expected to initiate in the second half of 2013. "We are pleased with the progress of our samatasvir program and its advancement into phase II following successful completion of a drug-drug interaction study with simeprevir earlier this year," said Ron Renaud, Idenix's President and Chief Executive Officer. "Our goal is to initiate multiple two- and three-DAA trials of samatasvir through the Janssen collaboration. Additionally, we look forward to advancing our own internal combination of samatasvir with our lead uridine nucleotide analog by the end of this year." ABOUT THE IDENIX/JANSSEN COLLABORATION In January 2013, Idenix entered into a non-exclusive collaboration with Janssen Pharmaceuticals, Inc. for the clinical development of all-oral direct-acting antiviral (DAA) HCV combination therapies. The collaboration will evaluate combinations including samatasvir, simeprevir, and TMC647055. In addition to the HELIX-1 phase II trial, the companies also plan to initiate HELIX-2 which will evaluate a three-DAA combination of samatasvir, simeprevir and TMC647055/r, with and without ribavirin. The clinical trials will be conducted by Idenix. Both Idenix and Janssen retain all rights to their respective compounds under the agreement.