Quartic CAR-T Cell Bridging to Twice Allo-HSCT Therapy in a Patient with Acute Lymphoblastic Leukemia

Introduction: Chimeric antigen receptor T (CAR-T) cell therapy is an effective bridging treatment for allogeneic hematopoietic stem cell transplantation (allo-HSCT) in relapsed or refractory acute lymphoblastic leukemia (ALL). However, repetitive CAR-T cell therapy and allo-HSCT can only be performed in a few patients because of technical difficulties and patients' physical, economic, and social conditions. Case Presentation: A 23-year-old female patient with second relapsed B-cell ALL (B-ALL) underwent human-murine chimeric CD19 CAR-T cell therapy twice, human-murine chimeric CD22 CAR-T cell therapy once, and humanized CD19 CAR-T cell therapy once. Moreover, she was sequentially bridged to her mother donor allo-HSCT once and cousin donor allo-HSCT once. Conclusion: Repetitive CAR-T cell therapy bridging to repetitive allo-HSCT is still a safe and active therapeutic strategy for patients with relapsed or refractory ALL.