• Patient able and willing to provide written informed consent and to comply with the study protocol and follow-up inspection.

• Histologically or cytologically confirmed metastatic adenocarcinoma of the colon; excluding appendiceal and anal canal cancers.

• Previously received at least second-line treatment, including two standard treatment regimens (such as fluoropyrimidine, capecitabine, irinotecan, oxaliplatin with or without anti-VEGF or anti-EGFR agents), if previously received first-line anti-EGFR therapy, achieving at least a partial response (PR) or above, with a discontinuation interval of at least one year.

• Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.

• Measurable disease by computed tomography (CT) or magnetic resonance imaging (MRI) (based on RECIST 1.1 criteria, with the longest diameter of tumor lesions on CT/MRI scan ≥10mm, and the shortest diameter of lymph node lesions on CT/MRI scan ≥15mm).

• Wild-type RAS/BRAF gene detected.

• Able to take oral medication.

• Normal organ function, meeting the following criteria within 14 days before treatment initiation:

‣ Neutrophil count ≥1.5×10\^9/L;

⁃ Platelet count ≥75×10\^9/L;

⁃ Hemoglobin ≥9.0g/dL;

⁃ Aspartate aminotransferase (AST) ≤2.5×upper limit of normal (ULN) (or ≤5×ULN if liver metastases);

⁃ Alanine aminotransferase (ALT) ≤2.5×ULN (or ≤5×ULN if liver metastases);

⁃ Total bilirubin ≤1.5×ULN;

⁃ Creatinine clearance (calculated by Cockcroft and Gault formula) \>60mL/min or serum creatinine ≤1.5×ULN;

• Expected survival time \>3 months (90 days).

⁃ Women of childbearing potential must have used reliable contraception for 7 days prior to enrollment, have had a negative pregnancy test, and agree to use appropriate contraception methods during the trial and for 6 months after the last dose of investigational drug. Men must agree to use appropriate contraception methods or have undergone surgical sterilization during the trial and for 6 months after the last dose of investigational drug.