Study Assessing Potential Predictive Tumor Markers in Metastatic Colorectal Cancer

Inclusion Criteria: * Man or woman ≥ 18 years. * Competent to comprehend, sign, and date an IEC-approved (Ethics Committee) informed consent form * Histologically-confirmed metastatic adenocarcinoma of the colon or rectum by the investigator. * Wild Type K-RAS colorectal cancer determined by the designated Central Laboratory prior to inclusion in the study in the primary tumor and/or at least one metastasis. * At least 1 uni-dimensionally measurable lesion of at least \> 10 mm with spiral CT per modified RECIST criteria 1.1. (Response Evaluation Criteria In Solid Tumors) * Patients with the following characteristics will be included: 1. Recurrence after adjuvant treatment with 5-fluorouracil/folinic acid or capecitabine +/- radiotherapy with a disease-free interval \> than 6 months after its completion. 2. Recurrence after adjuvant treatment with oxaliplatin +/- radiotherapy with a disease-free interval \> than 12 months 3. De novo diagnosis of the disease. * Eastern Cooperative Oncology Group performance status of 0 or 1. * Life expectancy ≥ 3 months * Adequate bone marrow function * Adequate Hepatic and metabolic functions * Adequate Renal function * Magnesium \> LLN (Lower limit of Normal) Exclusion Criteria: * Patients they have received prior systemic therapy for the treatment of metastatic colorectal carcinoma. * Prior anti-EGFr antibody therapy (eg, cetuximab) or treatment small molecule EGFr tyrosine kinase inhibitors (eg, erlotinib) or EGFR signal transduction inhibitors. * Patients who had resection of metastatic disease * Central nervous system/brain metastases * Prior malignant tumor in the last 5 years, except a history of basal cell carcinoma of the skin or pre-invasive cervical cancer. * Unresolved toxicities from prior systemic therapy that, in the opinion of the investigator, does not qualify the patient for inclusion * Presence of peripheral neuropathy (Common Toxicity Criteria (CTC) version 3.0 \> grade 1), and of serious nonhealing wound, ulcer, or bone fracture. * Hormonal therapy, immunotherapy or experimental or approved proteins/antibodies (eg, bevacizumab) ≤ 30 days before inclusion * Significant cardiovascular disease including unstable angina or myocardial infarction within 12 months before initiating study treatment or a history of ventricular arrhythmia. * History of interstitial pneumonitis or pulmonary fibrosis or evidence of interstitial pneumonitis or pulmonary fibrosis on baseline chest CT scan * Treatment for systemic infection within 14 days before initiating study treatment * Acute or sub-acute intestinal occlusion and /or active inflammatory bowel disease or other bowel disease causing chronic diarrhea (defined as \> 4 loose stools per day). * Known positive test for human immunodeficiency virus infection, hepatitis C virus, chronic active hepatitis B infection * Any investigational agent within 30 days before enrollment * Subject who is pregnant or breast feeding * Surgery (excluding diagnostic biopsy or central venous catheter placement) and/or radiotherapy within 14 days prior to inclusion in the study. * Woman or man of childbearing potential not consenting to use adequate contraceptive precautions