This is an open-label, single-arm clinical study designed to evaluate the efficacy and safety of IL-5 CAR-T cell therapy in the treatment of patients with CD125-positive eosinophilic leukemia.

The IL-5 CAR is composed of full length human IL-5 (hIL-5) fused to the human CD8α hinge and transmembrane domains, followed by the human 4-1BB co-stimulatory domain and the CD3ζ signaling domain. Prior to CAR-T cell infusion, the patients will be subjected to preconditioning treatment. After CAR-T cell infusion, the patients will be evaluated for adverse reactions and efficacy.

The Main research objectives:

To evaluate the safety and efficacy of IL-5 CAR-T cells in patients with CD125-positive eosinophilic leukemia.

The Secondary research objectives:

To investigate the cytokinetic characteristics of IL-5 CAR-T cells in patients with CD125-positive eosinophilic leukemia.

Inclusion Criteria:

• 1.Male or female patients aged ≥18 years;
• 2.Diagnosis of eosinophilic leukemia (EL) established according to the WHO 2022 diagnostic criteria;
• 3.Interleukin-5 receptor α (IL-5Rα, CD125) is expressed on ≥50% of leukemic blasts.
• 4.Meet any of the following criteria for refractory/relapsed eosinophilic leukemia:
• a) Inadequate response to standard therapy: failure to achieve complete remission (CR) after standard treatments (e.g., imatinib, corticosteroids, interferon-α, chemotherapy, etc.);
• b) Disease progression/relapse within 6 months after achieving remission;
• 5.Serum total bilirubin ≤1.5 × the upper limit of normal (ULN), and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤3 × ULN;
• 6.Left ventricular ejection fraction (LVEF) >50% as assessed by echocardiography;
• 7.Peripheral oxygen saturation (SpO₂) ≥92% on room air (without supplemental oxygen);
• 8.Estimated life expectancy >3 months;
• 9.Eastern Cooperative Oncology Group (ECOG) performance status 0-1;
• 10.Women and men of childbearing potential must agree to use appropriate, effective contraception prior to study entry, throughout the study period, and for 6 months after cell infusion (the safety of this therapy for unborn children is unknown and may pose potential risks);
• 11.Patients who are willing to participate in this study and who are able to understand and voluntarily sign the written informed consent form.

Exclusion Criteria:

• 1.History of epilepsy or other central nervous system (CNS) disorders;
• 2.Presence of any of the following:Hepatitis B surface antigen (HBsAg)-positive; Any of HBeAg, HBeAb, or HBcAb positive and detectable hepatitis B virus (HBV) DNA in peripheral blood above the lower limit of detection; Hepatitis C virus (HCV) antibody-positive; Human immunodeficiency virus (HIV) antibody-positive; Positive serologic test for syphilis;
• 3.History of QT interval prolongation or severe cardiac disease;
• 4.Presence of uncontrolled active infection;
• 5.Any condition that, in the opinion of the investigator, may increase the risk to the subject or interfere with the interpretation of the study results.