• The age is 18 to 75 years (including boundary values) and the gender is not limited;

• Patients with advanced GI tumors diagnosed by pathohistology, mainly:

∙ (1)Patients with metastatic colorectal cancer who have failed or are intolerant to second-line and above standard therapy;

∙ Notes:

• The standardized systemic treatment received by the patient must be in accordance with the Chinese Society of Clinical Oncology (CSCO) Guidelines for the Treatment of Colorectal and Gastric Cancer, 2024 Edition;

• Claims of treatment intolerance: Patients who are unable to continue current effective systemic standardized treatment due to toxic side effects such as grade ≥3 vomiting, diarrhea, abdominal pain, bone marrow suppression, etc., and who do not accept refusal for financial and personal reasons; 3.Presence of at least one measurable lesion that meets RECIST 1.1 criteria; 4.Patients must provide a tumor sample within 2 years that meets the requirements (paraffin block or number of unstained sections that meet the testing requirements set by the Institute) that is positive for GUCY2C expression by immunohistochemistry; 5.Survival is expected to be more than 3 months; 6.Eastern cooperative oncology group (ECOG) score of 0-1 (refer to Attachment 2); 7.Women of childbearing potential who have a negative blood pregnancy test prior to the start of the trial and who agree to use effective contraception during the trial and up to the last follow-up visit; male patients whose partners are of childbearing potential agree to use effective contraception during the trial and up to the last follow-up visit 8.Laboratory tests should meet at least the indicators specified below:

‣ Hemoglobin (Hb) ≥ 90 g/L;

⁃ Neutrophil count (Absolute neutrophil count, ANC) ≥ 1.5 x 10\^9/L;

⁃ Platelet count (PLT) ≥ 75 x 10\^9/L;

⁃ Absolute lymphocyte value ≥ 0.6 x 10\^9/L;

⁃ Lymphocytes make up ≥10% of white blood cells;

⁃ Creatinine clearance ≥60 ml/min;

⁃ Alanine transaminase (ALT) and Aspartate aminotransferase (AST) ≤ 2.5 x ULN and total bilirubin (TBL) ≤ 1.5 x ULN (for elevations of ALT and AST that can be explained by hepatic aggression, the high limits for AST and ALT can be adjusted upward to 5-fold, and the high limit for TBL may be adjusted upward to 3-fold;

⁃ Serum albumin ≥ 3.0 g/dL.

⁃ Prolongation of prothrombinogen time ≤ 4s; 9.Left ventricular ejection fraction ≥ 50% with a normal ECG or an abnormal ECG that, in the judgment of the investigator, does not require treatment; 10.Oxygen saturation \>92% in non-oxygenated state; 11.Vascular access is adequate for cell collection, and lines are available for patients with existing central venous catheters; Those who voluntarily participate in the trial and sign the informed consent form