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

Inclusion Criteria: * 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. * 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. * Estimated survival duration exceeding 3 months as of the date of informed consent signing. * Participants with Eastern Cooperative Oncology Group (ECOG) physical status scores ranging from 0 to 2. * Age range of 14 years ≤ ≤ 75 years, inclusive, with no gender restriction. * Hemoglobin (HGB) level ≥70 g/L with transfusion capability. * 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. * Acceptance of autologous CART cells with peripheral blood tumor burden ≤ 30%; * The subject or guardian understands and signs the informed consent form. Exclusion Criteria: * Presence of one of the following cardiac criteria: 1. Atrial fibrillation; 2. Myocardial infarction (MI) within the past 12 months; 3. Prolonged QT syndrome or secondary QT prolongation as determined by the investigator; 4. Echocardiographic left ventricular systolic fraction (LVSF) \<30% or left ventricular ejection fraction (LVEF) \<50%; 5. Clinically significant pericardial effusion; New York Heart Association (NYHA) class III or IV heart failure (confirmed by echocardiography within 12 months after treatment). * Active graft-versus-host disease (GVHD). * History of severe pulmonary dysfunction. * Concurrent other progressive malignancies. * Concurrent severe or persistent infections that cannot be effectively controlled. * Concurrent severe autoimmune diseases or congenital immunodeficiency. * 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). * Human immunodeficiency virus (HIV) infection or syphilis infection. * History of severe allergic reactions to biological products (including antibiotics). * Presence of central nervous system disorders such as uncontrolled epilepsy, cerebrovascular ischemia/hemorrhage, dementia, or cerebellar diseases. * Female patients in pregnancy or lactation, or planning pregnancy within 12 months. * Situations where investigators consider may increase subject risk or interfere with trial outcomes.