The purpose of this study is to evaluate and quantify the dynamic modifications of tumor blood perfusion on axitinib therapy in patients with refractory mCRC for each dose of Axitinib.

Inclusion Criteria:

• Patients with histologically confirmed diagnosis of CRC
• Measurable metastatic disease to the liver in proven disease progression (according to RECIST criteria) at baseline (within 4 weeks prior to study entry), with at least one lesion > 2cm considered appropriate for DCE-US examination
• Previously exposed to at least, irinotecan, oxaliplatin and a fluoropyrimidine, all 3 administered at optimal doses, over one or two chemotherapy (CT) lines for metastatic disease with a clear resistance to these drugs. Previous exposure to bevacizumab and/or anti-EGFR monoclonal antibody is allowed.
• Age ≥18 years; Performance Status (PS) 0-2 and life expectancy > 3 months.
• Adequate biological functions: Neutrophils ≥ 1.5 x 109/L; Platelets ≥ 100 x 109/L; Hemoglobin > 9 g/dl; Creatinine clearance > 30 ml/min (cockcroft & Gault formula). Serum bilirubin < 1,5 x the upper normal limit (UNL) and AST/ALT < 5 x UNL.
• Signed written informed consent
• Female patients with childbearing potential (<2 years after last menstruation) and male must use effective means of contraception during the study treatment and at least 6 months after the last study drug administration.