This study is to assess the efficacy and safety of Endostar combined with mFOLFOX6 in untreated metastatic colorectal cancer patients, and to find the markers that may predict the efficacy.

Inclusion Criteria:

• Histologically or cytologically confirmed metastatic colorectal cancer (adenocarcinoma)
• At least one measurable lesion (RECIST criteria)
• Life expectancy ≥ 3 months
• ECOG performance status 0-2
• Adequate hematologic function: ANC ≥ 1.5×109 /L，Hb ≥ 90 g/L，PLT ≥ 100×109 /L
• Adequate renal function: Cr ≤ 1.25×ULN or Creatinine clearance ≥ 60 ml/min
• Adequate hepatic function: BIL ≤ 1.5×ULN, ALT/AST ≤ 2.5×ULN, Alkaline phosphatase ≤ 5×ULN
• Patients have not previously received palliative chemotherapy, immunological/ biological treatment
• No adjuvant chemotherapy in last six months
• Target lesion has not received local radiotherapy
• Written informed consent

Exclusion Criteria:

• Diagnosis of colorectal neuroendocrine tumor, undifferentiated carcinoma, adenosquamous carcinoma, squamous cell carcinoma
• Evidence of serious or uncontrolled infection
• Serious cardiovascular disease (congestive heart failure, uncontrollable arrhythmia, unstable angina, myocardial infarction, serious heart valve disease, resistant hypertension)
• Pregnant or lactating women
• Women of childbearing potential refused to practice acceptable methods of birth control to prevent pregnancy
• Allergic to any of the study drug
• Intestinal obstruction, intestinal perforation, or stroke within 3 months
• Participation in other clinical studies