Optimised CD33 (FL-33) CAR T Therapy for Refractory/Relapsed Acute Myeloid Leukaemia

Inclusion Criteria: * Patients who met all the inclusion criteria were eligible for enrolment. 1. Patients diagnosed with primary resistance acute myeloid leukemia, tumour surface antigen CD33 expression, chemotherapy relapse, extramedullary relapse, persistent residual positivity or relapse/refractory after allogeneic haematopoietic stem cell transplantation; 2. Age 1-70 years old; 3. No severe allergies; 4. Physical condition: 0-2 ECOG score; 5. Expected survival ≥ 60 days; 6. Bone marrow or cerebrospinal fluid tumour cells are positive for CD33 by flow cytometry assay or tumour tissues positive for CD33 by immunohistochemistry (CD33 determination of positivity: flow cytometry: \>80% of tumour cells expressing CD33 and MFI similar to normal myeloid cells is considered as full positivity; tumour cells greater than 80% of expression of CD33 but MFI lower than the CD33 expression of normal myeloid cells by 1 log is considered as low expression (dim). Tumour cells with between 20-80% positive CD33 expression are partially expressed; Pathological immunohistochemistry: tumour cells\>30% positive are considered to be positively expressed; 7. Self-aware patients aged 19-70 years are required to voluntarily sign an informed consent form in writing; paediatric patients aged 1-7 years can be recruited after their legal representative (guardian) had signed an informed consent form; self-aware paediatric patients aged 8-18 years voluntarily sign an informed consent form in writing, and their legal representative (guardian) are required to sign an informed consent form in writing as well; 8. Suitable and available allogeneic haematopoietic stem cell transplant donors are required, and allogeneic haematopoietic stem cell transplantation can be performed after receiving FL-33 CAR T treatment. Exclusion Criteria: * Patients who fulfil any of the following criteria may not be enrolled. 1. Patients with history of allogeneic HSCT but PBMNC is not available from prior- transplant donor for preparation of CAR T cells and peripheral blood tumour load \>30%; patients without history of allogeneic HSCT and peripheral blood tumour load \>30%; 2. Intracranial hypertension or cerebral impaired consciousness; 3. Symptomatic heart failure or severe arrhythmia; 4. Symptoms of severe respiratory failure; 5. With other types of malignancy; 6. Diffuse intravascular coagulation; 7. Serum creatinine and/or urea nitrogen ≥ 1.5 times the normal value; 8. With sepsis or other uncontrollable infection; 9. Suffering from uncontrollable diabetes mellitus; 10. Severe mental disorders; 11. Have significant intracranial lesions on cranial MRI; 12. Organ transplantation (excluding haematopoietic stem cell transplantation) history; 13. Female patients (patients of childbearing potential) with positive blood HCG test; 14. Hepatitis (including hepatitis B and C) and positive screening for AIDS and syphilis.