Novel Anti-CD19 Universal CAR-T Cells for r/r CD19+ B-ALL

Inclusion Criteria: 1. Male or female, aged 2-75 years; 2. A definite diagnosis of relapsed/refractory B-ALL and a percentage of primitive/naive lymphocytes \>5% in bone marrow at baseline (flow cytometry); 3. CD19 expression was positive in bone marrow or peripheral blood tumor cells; 4. ECOG score 0-2 points; 5. Expected survival time ≥3 months; 6. Adequate liver, kidney, heart and lung function; 7. Patients who have recovered from acute toxic effects of prior chemotherapy should be excluded from the trial at least one week apart; 8. Women of childbearing age have negative blood pregnancy test before the start of the trial, and agree to take effective contraceptive measures during the trial until the last follow-up; male subjects with partners of childbearing potential agree to take effective contraceptive measures during the trial until the last follow-up; 9. Voluntarily sign the informed consent. Exclusion Criteria: 1. Presence of other concurrent active malignancy; 2. People with severe mental disorders; 3. A history of any of the following genetic disorders, such as Fanconi anemia, Schu-Day syndrome, Gerstmann syndrome, or any other known bone marrow failure syndrome; 4. Acute GVHD of grade II-IV or extensive chronic GVHD; 5. Had grade III-IV heart failure or myocardial infarction, cardiac angioplasty or stenting, unstable angina pectoris, or other clinically prominent heart disease within one year prior to enrollment; 6. The presence of any indwelling catheter or drainage (e.g., percutaneous nephrostomy, indwelling catheter, bile drainage, or pleural/peritoneal/pericardial catheter), except for patients who are permitted to use dedicated central venous catheters; 7. A history or disease of the central nervous system(CNS), such as seizure disease, cerebrovascular ischemia/bleeding, dementia, cerebellar disease, or any autoimmune disease involving the CNS; 8. Human immunodeficiency virus (HIV) seropositivity; Hepatitis B surface antigen positive or hepatitis B core antibody positive, and HBV-DNA positive; Patients with hepatitis C (HCV-RNA quantitative test results positive); Or the presence of other serious active viral or bacterial infections or uncontrolled systemic fungal infections; 9. Patients with severe history of allergy or allergic constitution; 10. A history of autoimmune diseases (e.g., Crohn's disease, rheumatoid arthritis, systemic lupus erythematosus) leading to end-organ damage or requiring systemic immunosuppressive/systemic disease modulating drugs within the past 2 years; 11. Had or is suffering from interstitial lung disease (e.g., pneumonia, pulmonary fibrosis); 12. Had undergone other clinical trials in the 4 weeks prior to participating in this trial; 13. Poor compliance due to physiological, family, social, geographical and other factors, unable to cooperate with the study protocol and follow-up plan; 14. For patients contraindicated with cyclophosphamide and fludarabine chemotherapy; 15. Subjects requiring systemic corticosteroid therapy (prednisone ≥5mg/ day or equivalent dose of another corticosteroid) or other immunosuppressive agents within 1 month after UCAR-T cell reinfusion, except for adverse events; 16. Receiving donor lymphocyte infusion within 6 weeks before enrollment; 17. Pregnant and lactating women; 18. Any other condition that the investigator deemed inappropriate for inclusion.