This is a phase II randomized study of 4-months induction first-line chemotherapy with FOLFOXIRI + cetuximab followed by maintenance with cetuximab or bevacizumab in patients affected by KRAS wild type (wt) mCRC.

The aim of the study is to obtain a rapid disease control with the therapy and the maximum tumoral shrinkage, and than to treat patient with less intensive maintenance to inhibit tumoral regrowth.

Inclusion Criteria:

• Histologically confirmed colorectal adenocarcinoma;
• Availability of formalin-fixed paraffin embedded tumor block from primary and/or metastasis;
• KRAS wild-type status of primary colorectal cancer or related metastasis;
• Unresectable and measurable metastatic disease according to RECIST criteria;
• Male or female, aged > 18 years and < 75 years;
• ECOG PS < 2 if aged < 71 years, ECOG PS = 0 if aged 71-75 years;
• Life expectancy of more than 3 months;
• Adequate haematological function: ANC ≥ 1.5 x 109/L; platelets ≥ 100 x 109/L, Hb ≥ 9 g/dL;
• Adequate liver and renal function: serum bilirubin ≤ 1.5 x ULN; alkaline phosphatase and transaminases ≤ 2.5 x ULN (in case of liver metastases < 5 x ULN); serum creatinine ≤ 1.5 x ULN;
• Previous adjuvant chemotherapy containing oxaliplatin is allowed if more than 12 months have elapsed between the end of adjuvant therapy and first relapse;
• Previous adjuvant chemotherapy with fluoropyrimidine monotherapy is allowed if more than 6 months have elapsed between the end of adjuvant and first relapse;
• At least 6 weeks from prior extended radiotherapy and 4 weeks from surgery;
• Written informed consent to experimental treatment and KRAS analysis.

Exclusion Criteria:

• Prior palliative chemotherapy;
• Prior treatment with EGFR or VEGF inhibitors;
• Symptomatic peripheral neuropathy > 2 grade NCIC-CTG criteria;
• Presence or history of CNS metastasis;
• Active uncontrolled infections; active disseminated intravascular coagulation;
• Past or current history of malignancies other than colorectal carcinoma, except for curatively treated basal and squamous cell carcinoma of the skin cancer or in situ carcinoma of the cervix;
• Clinically significant cardiovascular disease: cerebrovascular accidents or myocardial infarction ≤ 12 months before treatment start, unstable angina, NYHA ≥ grade 2 chronic heart failure, uncontrolled arrhythmia, uncontrolled hypertension;
• Serious, non-healing wound, ulcer, or bone fracture;
• Evidence of bleeding diathesis or coagulopathy;
• Major surgical procedure or significant traumatic injury within 28 days prior to study treatment start;
• Current or recent (within 10 days prior to study treatment start) ongoing treatment with anticoagulants for therapeutic purposes or chronic, daily treatment with high-dose aspirin (>325 mg/day);
• Subtotal colectomy, malabsorption syndrome and chronic inflammatory bowel disease (i.e. ulcerative colitis, Chron syndrome);
• Fertile women (<2 years after last menstruation) and men of childbearing potential not willing to use effective means of contraception.
• Psychiatric disorder precluding understanding of information on trial related topics,
• Serious underlying medical condition (judged by the investigator) which could impair the ability of the patient to participate in the trial (e.g. uncontrolled diabetes mellitus, active autoimmune disease)
• Concurrent treatment with other experimental drugs or other anti-cancer therapy; treatment in a clinical trial within 30 days prior to trial entry
• Definite contraindications for the use of corticosteroids and antihistamines as premedication
• Known hypersensitivity to trial drugs or hypersensitivity to any other component of the trial drugs
• Any concomitant drugs contraindicated for use with the trial drugs according to the product information of the pharmaceutical companies
• Pregnancy
• Any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule; those conditions should be discussed with the patient before registration in the trial
• Medical or psychological condition which, in the opinion of the investigator, would not permit the patient to complete the study or sign meaningful informed consent