Functionally Optimized CD33 CAR-T Cell Therapy Targeting Recurrent/Refractory Acute Myeloid Leukemia

Inclusion Criteria: * 1\. Subjects diagnosed with refractory/recurrent acute myeloid leukemia (excluding M3) who meet any of the following criteria: 1. Relapse: Recurrence of leukemia cells in peripheral blood or ≥5% blast cells in bone marrow after complete remission (CR) of AML (excluding other causes such as bone marrow regeneration following consolidation chemotherapy), or extramedullary leukemia infiltration. 2. Refractory: First-time cases unresponsive to two cycles of standard therapy; relapse within 12 months after consolidation therapy following CR; relapse after 12 months without response to conventional chemotherapy; two or more relapses; persistent extramedullary leukemia. 2\. During enrollment screening, bone marrow flow cytometry must demonstrate a CD33+ expression rate of ≥80% in leukemia cells and/or pathological immunohistochemical confirmation of CD33+ extramedullary lesions; 3. Estimated survival duration exceeding 3 months as of the date of informed consent signing; 4. Participants with Eastern Cooperative Oncology Group (ECOG) physical status scores ranging from 0 to 2; 5. Age range of 14 years ≤ ≤ 75 years, inclusive, with no gender restriction; 6. Hemoglobin (HGB) level ≥70 g/L with transfusion capability; 7. Liver/kidney function and cardiopulmonary function meeting the following criteria: <!-- --> 1. Creatinine ≤1.5×ULN; 2. Left ventricular ejection fraction ≥50%; 3. Blood oxygen saturation\>90%; 4. Total bilirubin ≤1.5×ULN; ALT and AST ≤2.5×ULN; 8. Acceptance of autologous CART cells with peripheral blood tumor burden ≤ 30%; 9. The subject or guardian understands and signs the informed consent form. Exclusion Criteria: * 1\. Presence of one of the following cardiac criteria: atrial fibrillation; myocardial infarction (MI) within the past 12 months; prolonged QT syndrome or secondary QT prolongation as determined by the investigator. Echocardiographic left ventricular systolic fraction (LVSF) \<30% or left ventricular ejection fraction (LVEF) \<50%; clinically significant pericardial effusion; New York Heart Association (NYHA) class III or IV heart failure (confirmed by echocardiography within 12 months after treatment). 2\. Active graft-versus-host disease (GVHD); 3. History of severe pulmonary dysfunction; 4. Concurrent other progressive malignancies; 5. Concurrent severe or persistent infections that cannot be effectively controlled; 6. Concurrent severe autoimmune diseases or congenital immunodeficiency; 7. Active hepatitis (HBV-DNA ≥ 500 IU/ml with abnormal liver function or HCV antibody \[HCV-Ab\] positivity, HCV-RNA exceeding the detection limit of analytical methods with abnormal liver function); 8. Human immunodeficiency virus (HIV) infection or syphilis infection; 9. History of severe allergic reactions to biological products (including antibiotics); 10. Presence of central nervous system disorders such as uncontrolled epilepsy, cerebrovascular ischemia/hemorrhage, dementia, or cerebellar diseases; 11. Female patients in pregnancy or lactation, or planning pregnancy within 12 months; 12. Situations where investigators consider may increase subject risk or interfere with trial outcomes.