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