FOLFOXIRI Compared to FOLFOX in First Line Treatment of Metastatic Colorectal Cancer

Inclusion Criteria:

* Signed informed consent obtained before any study specific procedures. -Subjects must be able to understand and willing to sign a written informed consent.
* Male or female subjects ≥ 18 years ≤ 75 years of age
* Patients must have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 2.(ECOG PS 0-2 for≥18 years ≤ 65 years of age ，ECOG PS 0-1 for \>65 years of age)
* Histological or cytological documentation of adenocarcinoma of the colon or rectum. All other histological types are excluded.
* There must be documentation by PET/CT scan, CT scan, MRI, or intraoperative palpation (at the time of resection of the primary colorectal tumor, if applicable) that the patient has evidence of metastases (Histologic confirmation of metastasis is not required.).
* At least one measurable lesion according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria measured within 4 weeks prior to registration.
* No previous chemotherapy or target therapy for metastatic disease (adjuvant chemotherapy for non-metastatic disease is allowed if terminated more than 6 months ago).
* In case of previous radiotherapy, at least one measurable lesion should be located outside the irradiated field.
* Adequate bone marrow, hepatic and renal function as assessed by the following laboratory requirements conducted within 7 days of starting study treatment:
* Leukocytes ≥ 3.0 x109/ L, absolute neutrophil count (ANC) ≥ 1.5 x109/ L, platelet count ≥ 100 x109/ L, hemoglobin (Hb) ≥9g/ dL.
* Total bilirubin ≤ 1.5 x the upper limit of normal (ULN).
* Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 5 x ULN.
* Alkaline phosphatase limit ≤ 5x ULN.
* Amylase and lipase ≤ 1.5 x the ULN.
* Serum creatinine ≤ 1.5 x the ULN.
* Calculated creatinine clearance or 24 hour creatinine clearance ≥ 50 mL/ min.

Exclusion Criteria:

* Previous palliative chemotherapy for metastatic disease，previous adjuvant chemotherapy including irinotecan or oxaliplatin within 6 months before random assignment.
* Previous or concurrent cancer that is distinct in primary site or histology from colorectal cancer within 5 years prior to randomization.
* Life expectancy \> 12 weeks;
* Extended field radiotherapy within 4 weeks or limited field radiotherapy within 2 weeks prior to randomization. Subjects must have recovered from all therapy-related toxicities.
* Major surgical procedure, open biopsy, or significant traumatic injury within 4 weeks before start of study medication.
* Congestive heart failure ≤ New York Heart Association (NYHA) class 2.
* Significant cardiovascular disease including unstable angina or myocardial infarction within 6 months before initiating study treatment or a history of ventricular arrhythmia
* Arterial or venous thrombotic or embolic events such as cerebrovascular accident (including transient ischemic attacks), deep vein thrombosis or pulmonary embolism within the 6 months before start of study medication.
* Any evidence of active infection.
* History of interstitial pneumonitis or pulmonary fibrosis
* Pregnancy or lactation at the time of study entry.
* Known dihydropyrimidine dehydrogenase (DPD) deficiency
* Any illness or medical conditions that are unstable or could jeopardize the safety of the subjects and his/her compliance in the study.
* Active inflammatory bowel disease or other bowel disease causing chronic diarrhoea
* Subjects with known allergy to the study drugs or to any of its excipients.
* Current or recent (within 4 weeks prior to starting study treatment) treatment of another investigational drug or participation in another investigational study.
* Continuous use of immunosuppressive agents (except the use of corticosteroids as anti-emetic prophylaxis/treatment).