A Phase II Study on Dose Optimization of Fruquintinib in Elderly mCRC Patients Refractory to Standard Treatment（DOFEMCRC）

Inclusion Criteria: 1. 65 years and older; 2. Histologically or cytologically confirmed unresectable metastatic colorectal cancer refractory to or unfit for standard therapies; 3. ECOG PS 0-1; 4. At least 4 weeks after the last anti-tumor therapy (chemotherapy, radiotherapy, biotherapy or hormone therapy) and more than 3 months after operation treatment before enrollment; 5. Life expectancy ≥ 3 months; 6. Cooperative in observation of adverse events and curative effect; 7. No other anti-tumor concomitant treatment (including steroid drugs); 8. Adequate organ and bone marrow functions; 9. At least one measurable lesion(s); 10. Signed the written informed consent and completed the geriatric questionnaire (G8 screening form) at the time of enrollment. Exclusion Criteria: 1. Active upper gastrointestinal ulcer, obvious vomiting, chronic diarrhea, intestinal obstruction, absorption disorder, etc which may affect drug absorption, distribution, metabolism, or clearance; 2. Evidence of central nervous system metastasis; 3. One of the following complications: uncontrolled hypertension, coronary artery disease, arrhythmia and heart failure; 4. Abuse of alcohol or drugs; 5. Less than 4 weeks from the last clinical trial; 6. Previous treatment with VEGFR inhibitors; 7. Severe uncontrolled disability with concurrent infection; 8. Proteinuria ≥ 2 + (1.0g / 24hr); 9. Uncontrollable gastrointestinal bleeding; 10. Arterial / venous thromboembolic events such as cerebrovascular accident (including transient ischemic attack) occurred within 12 months before the first dose; 11. Acute myocardial infarction, acute coronary syndrome or coronary artery bypass grafting occurred within 6 months before the first dose; 12. Fracture or wound that has not been cured for a long time; 13. Coagulation dysfunction, bleeding tendency or receiving anticoagulation treatment; 14. Congenital or acquired immune deficiency (such as HIV infection), or active hepatitis (HBV DNA ≥ 103copies / ml after regular antiviral therapy); 15. Patients who are not suitable for the study judged by the researchers.