To control apatinib and capecitabine combination to maintain treating metastatic colorectal cancer.

To control apatinib and capecitabine combination to maintain treating metastatic colorectal cancer,primary endpoint include in mPFS; secondary endpoint include in mOS, tolerance and security.

Inclusion Criteria:

1. Informed consent form should be issued prior to conducting any research process;

2. Men or women aged 18-75 years;

3. Patients with advanced and / or metastatic colorectal cancer confirmed by histology or cytology;

4. Patients who has not exposed to apatinib previously and had received oxaliplatin combined with fluorouracil chemotherapy;

5. The estimated survival time is longer than 3 months;

6. ECOG score was 0 or 1;

7. According to the RECIST v1.1 guidance, at least 1 lesion(who had not received radiotherapy) showed that the longest diameter≥10mm(except for lymph node, the short axis of the lymph node must be≥15mm) through CT or MRI(intravenous contrast agent was preferred ) accurate measurement and the lesion should be suitable for repeatable and accurate measurement; the lesion located in the previously irradiated area can be used as a measurable lesion if the lesion was proved in progress;

8. With sufficient organ and bone marrow function, defined as follows:

   • Hb≥9 g/dL
   • Absolute neutrophil count ≥1.0 × 109 /L
   • Platelet count≥75 × 109 /L
   • Serum bilirubin ≤ 1.5 × ULN, which would not be appropriate for patients with Gilbert syndrome (Persistent or recurrent hyperbilirubinemia, mainly unconjugated bilirubin, with no evidence of hemolysis or abnormal liver pathology) which can consult a doctor
   • ALT&AST ≤ 2.5 × ULN; for patients with liver metastases, ALT&AST ≤ 5 × ULN Calculate the creatinine clearance rate by Cockcroft-Gault formula
   • Creatinine clearance rate measured( by actual body weight) or by measuring urine collection for 24 hours> 40 mL/min(the value of the measurement of the 24 - hour urine collection will be used to determine eligibility if the two methods are used)

9. Women of childbearing age must have a pregnancy test (serum or urine) within 7 days before inclusion, the results should be negative and they are willing to use the appropriate methods of contraception during the trial and within 6 months of the last experimental drug administration. Men should agree to use appropriate methods of contraception during the trial and within 6 months of the last experimental drug administration;

10. Patients volunteered to participate in the trial and signed informed consent form with good compliance.

Exclusion Criteria:

1. Patients with hypertension and can not be reduced to the normal range with antihypertensive drugs(systolic pressure >140 mmHg / diastolic pressure > 90 mmHg),patients with coronary heart disease more than grade II, arrhythmia (including QTc interval Prolongation men>450 ms, women >470 ms) and cardiac insufficiency;
2. With a variety of factors affecting oral drugs(such as unable to swallow, nausea and vomiting, chronic diarrhea and intestinal obstruction, etc.);
3. Special note: patients with the risk of gastrointestinal bleeding can not be included, including the following: active peptic ulcer lesions and fecal occult blood (+ +); patients with melena and hematemesis in 3 months; for patients with fecal occult blood (+) and primary gastric tumor without surgery should be carried out gastroscopy, patients with ulcero carcinoma of stomach and believed to cause the lesion to bleed by the physician;
4. Abnormal coagulation function(INR>1.5×ULN、 APTT>1.5×ULN) with bleeding tendency;
5. With Symptomatic central nervous system metastasis;
6. Pregnant or lactating women;
7. Other patients unsuitable for inclusion considered by the physician.