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.

• 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;
• Age 1-70 years old;
• No severe allergies;
• Physical condition: 0-2 ECOG score;
• Expected survival ≥ 60 days;
• 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;
• 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;
• 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.

• 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%;
• Intracranial hypertension or cerebral impaired consciousness;
• Symptomatic heart failure or severe arrhythmia;
• Symptoms of severe respiratory failure;
• With other types of malignancy;
• Diffuse intravascular coagulation;
• Serum creatinine and/or urea nitrogen ≥ 1.5 times the normal value;
• With sepsis or other uncontrollable infection;
• Suffering from uncontrollable diabetes mellitus;
• Severe mental disorders;
• Have significant intracranial lesions on cranial MRI;
• Organ transplantation (excluding haematopoietic stem cell transplantation) history;
• Female patients (patients of childbearing potential) with positive blood HCG test;
• Hepatitis (including hepatitis B and C) and positive screening for AIDS and syphilis.