The objective is to investigate the efficacy and safety of raltitrexed-based chemotherapy plus bevacizumab in the treatment of advanced colorectal cancer

Inclusion Criteria:

• 18-70 years;
• histological and/or cytological confirmation of ACC;
• disease progression while on first-line palliative fluoropyrimidine-based chemotherapy or relapse within 6 months after adjuvant chemotherapy;
• at least one measurable objective tumor lesion by spiral CT examination, the maximum diameter ≥ 1cm（according to RECIST 1.1）
• ECOG performance status 0-1
• life expectancy of at least 3 months
• satisfactory main organ function，laboratory test must meet the following criteria: hemoglobin (HGB) ≥90g/L, neutrophil count（ANC） ≥1.5×109/L, platelet count（PLT） ≥80×109/L, Serum creatinine（CR）≤1.5 upper normal limitation (UNL)，total bilirubin (TBil) ≤1.5 upper normal limitation (UNL), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤2.5 UNL (For patients with liver metastasis, the AST/ALT must be ≤5.0 UNL), Alkaline phosphatase（ALP）≤3 UNL(For patients with liver metastasis, the ALP must be ≤5.0 UNL);
• written informed consent

Exclusion Criteria:

• prior exposure to raltitrexed;
• Clinically significant cardiovascular disease, for example symptomatic coronary artery disease, myocardial infarction (<=6 months before treatment start),congestive heart failure （New York Heart Association ，NYHA>= grade 3）,stroke or transient ischemic attack
• Accept kidney dialysis treatment now
• chronic enteropathy on unresolved bowel obstruction;
• previous malignant disease other than carcinoma in situ of the cervix or basal cell carcinoma of the skin;
• the UGT1A1 *28（7/7）*6（A/A） gene type;
• pregnant or lactated women;
• Unsuitable for the study or other chemotherapy determined by investigator.