A Phase I/II Study of XELOXIRI and Bevacizumab as First-line Treatment in Metastatic Colorectal Cancer

Inclusion Criteria: * Patients with histologically confirmed metastatic colorectal adenocarcinoma; * Age 18-80 years old; * Eastern Cooperation Oncology Group (ECOG) performance score(\<2); * At least one measurable lesion for disease assessment according to RECIST version 1.1; * Able to take oral medications; * Previous fluoropyrimidine-based adjuvant or neoadjuvant chemotherapy was allowed only when it ended ≥ 6 months before study enrollment; * No previous therapy for mCRC; * Adequate organ functions as assessed by the following laboratory requirements: Leukocytes≥3.0x109/L, absolute neutrophil count≥1.5x109/L, platelet count≥100x109/L, hemoglobin≥9g/dL; serum bilirubin≤1.5x the upper limit of normal(ULN);Alanine aminotransferase(ALT) and aspartate aminotransferase(AST)≤3x ULN; serum creatinine≤1.5x ULN; calculated creatinine clearance or 24 hour creatinine clearance ≥60ml/min. * An expected survival of at least 3 months; * Willingly provide written informed consent to study procedures. Exclusion Criteria: * Patients with dysphagia, active peptic ulcer, intestinal obstruction, active gastrointestinal bleeding, peptic perforation, malabsorption syndrome or uncontrolled intestinal inflammatory diseases; * With a history of extensive enterotomy or pelvic radiation therapy; Suffering from grade 2 or higher symptomatic peripheral neuropathy according to National Cancer Institute Common Toxicity (NCI-CTC) criteria; * Uncontrolled central nervous system metastasis, disseminated intravascular coagulation or active infection; * With concurrent cancer distinct from colorectal adenocarcinoma except cured skin basal cell carcinoma and cervical carcinoma in situ; * Undergone a major operation, open biopsy or major traumatic injury within 28 days before study enrollment or have potential to receive major operation during the trial; * Received central venous access device within 2 days before study enrollment; * Any kind of concurrent cardiac disease with clinical meanings, such as cardiovascular accident, myocardial infarction, thromboembolism or hemorrhage within 6 months before enrollment, congestive heart failure ≤New York Heart Association (NYHA) class 2 or uncontrolled hypertension. * With positive urine protein and 24-hour urinary protein content\>1g; * Have a tendency of bleeding or clotting; * With nasty open wounds, ulcers or fractures; * Current or recent treatment of anticoagulants, antiplatelet agent or nonsteroidal anti-inflammatory drugs, while aspirin of daily dose less than 325mg is allowed. * With any illness or medical conditions that may jeopardize the patient's compliance or interfere the analyses or judgements of study results; * Pregnancy or lactation at the time of study entry; * With fertility but refuse to contraception.