Biomarker Directed Treatment in Metastatic Colorectal Cancer

Inclusion Criteria: 1.1 Inclusion criteria for pre-screening phase: * Untreated advanced metastatic colorectal cancer patients * Adequate tissue to evaluate for genotyping (10 x 10µm thick formalin fixed paraffin embedded tissue sections and one corresponding HE stained slide or a FFPE tumor block) 1.2 Inclusion criteria for treatment phase: Patients must fulfill all criteria listed below prior to enrolment in the study: * Untreated wild-type KRAS metastatic colorectal cancer * Previous adjuvant therapy must have been completed \> 6 months before therapy initiation on this study * Age \>18 years * Measureable disease with CT or MRI * ECOG performance status of 0-2 * Adequate organ function * Hematologic: * Absolute neutrophil count \> 1,500/µL * Hemoglobin \>9 mg/dl * Platelet count \>100,000 /µl * Renal: * Serum creatinine \<1.5 x Upper limit of normal (UPN) or estimated clearance \> 30 ml/min * Hepatic: * Serum bilirubin \< 1.5 mg/dl Exclusion Criteria: * Creatinine clearance below 30 ml/min * Patients with a history of other malignancies within 2 years prior to study entry, except for adequately treated carcinoma in situ of the cervix; basal or squamous cell skin cancer; low grade, early stage localized prostate cancer treated surgically with curative intent; good prognosis DCIS of the breast treated with lumpectomy alone with curative intent. * Patients with a history of severe cardiac disease; e.g. NYHA Functional Class III or IV heart failure, myocardial infarction within 6 months, ventricular tachyarrhythmias requiring ongoing treatment, or unstable angina. * Other known co-morbidity with the potential to dominate survival * Hypersensitivity with anaphylactic reaction to humanized monoclonal antibodies or any of the applied drugs * Pregnant or breast feeding women * Any co-existing medical or psychological condition that would preclude participation in the study or compromise ability to give informed consent.