• Age ≥ 18 years old and ≤ 75 years old, gender is not limited;

• Diagnosis of colorectal cancer by histopathology and/or cytology, clinical Records showing inoperable advanced metastatic colon or rectal cancer (ie, stage IV according to the UICC AJCC TNM staging system \[8th edition 2017\]) ;

• At least 1 measurable target lesion according to RECIST v1.1 criteria (ie, non-nodal lesions with a CT scan length ≥10 mm and nodal lesions with a CT scan short diameter ≥15 mm) ;

• Prior first- or second-line oxaliplatin-based therapy with treatment failure or intolerance\*; Note: \*Treatment failure or intolerance is defined as (1) disease progression during treatment or disease progression within 6 months of final treatment, both with clear evidence of imaging or clinical progression, and (2) patients who withdrew from treatment because of intolerance of an adverse event of the treatment, as per NCI-CTCAE v5.0 criteria, intolerance is defined as: a. Hematological toxicity: grade III neutropenia accompanied by fever \>38.5°C, grade III thrombocytopenia with bleeding symptoms, and other grade IV or higher hematologic toxic reactions; b. Non-hematological toxicity: grade III or higher non-hematological toxic reactions; and c. Achievement of the above toxic reactions, which in the judgment of the investigator make continuation of the original regimen of Treatment.

• ECOG physical status score 0-1;

• Expected survival time ≥ 3 months;

• No major organ dysfunction, that is, the subject's organ function level and related laboratory indicators must meet the following requirements within 14 days before the first medication: (1) Blood routine (no blood transfusion, platelet transfusion, growth factors and other supportive treatments): white blood cells (WBC) ≥ 3.0 × 109/L; Absolute neutrophil count (ANC) ≥ 1.5 × 109/L; Platelet count (PLT) ≥ 100 × 109/L; Hemoglobin (Hb) ≥ 90 g/L; (2) Blood biochemistry: serum albumin (ALB) ≥ 30 g/L; Alanine aminotransferase (ALT)/aspartate aminotransferase (AST) ≤ 2.5 times the upper normal value (ULN), and if there is liver metastasis, ALT/AST ≤ 5 × ULN; Total bilirubin (TBIL) ≤ 1.5 × ULN; Serum creatinine (Cr) ≤ 1.5 × ULN, or endogenous creatinine clearance ≥ 60 mL/min according to the Cockcroft-Gault formula; (3) Urine routine: urine routine indicates urine protein \< + +; If the urinary protein at baseline is ≥ + +, it is necessary to confirm that the 24-hour urinary protein quantification is ≤ 1.0 g; (4) Coagulation function (within 14 days before the first dose): prothrombin time (PT) or activated partial thromboplastin time (aPTT) ≤ 1.5 × ULN, international normalized ratio (INR) ≤ 1.5 × ULN (no anticoagulant therapy); If the subject is treated with a stable dose of anticoagulant or vitamin K antagonist (such as warfarin, heparin or their analogues), on the premise that the international normalized ratio (INR) of prothrombin time is ≤ 1.5, it is allowed to use low-dose warfarin (1 mg orally once a day) or low-dose aspirin (not exceeding 100 mg a day) for preventive purposes; (5) Cardiac function: normal 12-lead electrocardiogram or abnormal 12-lead electrocardiogram without clinical significance judged by the investigator (i.e., QTcF \< 450 ms in men, QTcF \< 470 ms in women); Left ventricular ejection fraction (LVEF) ≥ lower limit of normal value (i.e., LVEF ≥ 50%).

• Other previous antineoplastic therapy should be terminated for 4 weeks or more, and the general physical condition or associated adverse effects have recovered (toxicity ≤1 grade) or reached a stable state;

• Serum pregnancy test must be negative and non-lactation period in women of childbearing age within 7 days before receiving the test Women of child-bearing age or men whose partners are women of child-bearing age must agree to use medically approved contraception (e.g. , Intrauterine device, male surgical sterilization, birth control pills or condoms) for the duration of the trial;

⁃ Voluntarily participate and sign an informed consent form; Ability to comply with research visit plans and other program requirements.