Inclusion criteria:
Inclusion criteria: Male or female aged 18-75 years at the time of signing the informed consent form, have been diagnosed as mCRC verified histologically, having one or more bi-dimensionally measurable lesions as defined by Response Evaluation Criteria In Solid Tumors (RECIST) criteria, was not felt to be amenable to curative resection, with an Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 1, life expectancy of longer than 3 months ( clinical assessment), adequate organ and marrow function as defined below: Absolute neutrophil count (ANC) greater than/equal to 1,500/mm3; o Platelets greater than/equal to 100,000/ mm3; o Hemoglobin greater than/equal to 9 gm/dl (may be transfused to maintain or exceed this level); o Total bilirubin less than/equal to 1.5 within institutional upper limit of normal (IULN); Aspartate aminotransferase (AST or SGOT)/alanine aminotransferase (ALT or SGPT) less than/equal to 2.5 times IULN, or less than/equal to 5 times IULN if known liver metastases, may have received adjuvant therapy for primary colorectal cancer provided that at least 6 months have elapsed from the time the adjuvant therapy was concluded and recurrent disease was documented, Patients with history of hypertension must be well-controlled (blood pressure less than/equal to 150/100mmHg), on a stable regimen of anti-hypertensive therapy.
Exclusion criteria:
Exclusion criteria, Radiotherapy or surgery for mCRC less than 4 weeks before random assignment, Undergone major surgical procedures or open biopsy within 28 days before the initiation of study treatment, experienced a significant traumatic injury, within 28 days before study entry, currently using or had recently used therapeutic anticoagulants, thrombolytic therapy, chronic, daily treatment with aspirin( higher than 325 mg/daily). (Patients may have prophylactic use of low molecular weight heparin, however therapeutic use of heparin or low molecular weight heparin is not acceptable) - Proteinuria exceeding 500mg/24h - History or presence of central nervous system metastases - Female patients who are pregnant or lactating - Patients with a history of allergic reactions attributed to compounds of similar chemical or biologic composition to bevacizumab, irinotecan, 5-FU, or leucovorin - Serious non-healing wound, ulcer, or an active bone fracture - Patients with any history of another primary malignancy less than/equal to 5 years, with the exception of non-melanoma skin cancer, and carcinoma in situ of the uterine cervix. - Myocardial infarction within 6 months before of study enrollment; - History of stroke within 6 months before of study enrollment; - Unstable symptomatic arrhythmia requiring medication; - Clinically significant peripheral vascular disease; - Uncontrolled diabetes; Serious active or uncontrolled infection - Inability to comply with study and/or follow-up procedures