Purpose of the trial is to evaluate the efficacy of Xaliproden in reducing the neurotoxicity of the Oxaliplatin and 5-FU/LV chemotherapy, in patients with metastatic colorectal carcinomaPrimary objectives : Compare the risk of occurence of grade 3-4 peripheral sensory neuropathy relative to the cumulative dose of Oxaliplatin between treatment group and placebo group ; Compare the response rate between treatment group and placebo group.Secondary objectives : neurotoxicity parameters (overall incidence, time and dose to onset, time to recovery, change in the sensory action potentials) ; antitumoral efficacy (progression-free survival, overall survival) ; safety profile.