OBJECTIVETo evaluate the safety and efficacy of chimeric antigen receptors T cells (CAR-T) in childhood acute B lymphoblastic leukemia (B-ALL).

METHODSA relapsed B-ALL child after allogeneic hematopoietic stem cell transplantation (allo-HSCT) was treated with CAR-T, and the related literatures were reviewed.

RESULTAn 11-year-old girl with TEL-AML1 fusion gene positive BALL who suffered a bone marrow relapse 28 months after remission from conventional chemotherapy. During the second remission, the patient received haploidentical allo-HSCT. She relapsed with detectable TEL-AML1 fusion gene even after chemotherapy and donor leukocyte infusions. She received an experimental donor-derived fourth generation CD19 CAR-T therapy. After infusion of 1 × 10(6)/kg CAR-T cells, she experienced only mild or moderate cytokine-release syndrome and the minimal residual disease turned negative. Then three maintenance of CAR-T cell infusions [(0.83-1.65)×10(6)/kg] was administered, and the disease-free survival had lasted for 10 months. However, the TEL-AML1 copies in her blood still increased and she died with leukemia relapse after additional CAR-T cell infusion.

CONCLUSIONTreatment of relapsed B-ALL with the fourth generation CAR-T cells directed against CD19 was effective and safe. CAR-T therapy is a novel therapeutic approach that could be useful for patients with relapsed and refractory B-ALL who have failed all other treatment options.

Bone Marrow ; Child ; Core Binding Factor Alpha 2 Subunit ; genetics ; Disease-Free Survival ; Female ; Hematopoietic Stem Cell Transplantation ; Humans ; Neoplasm, Residual ; Oncogene Proteins, Fusion ; genetics ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; genetics ; therapy ; Receptors, Antigen, T-Cell ; genetics ; Recurrence ; Remission Induction ; T-Lymphocytes ; cytology ; Transplantation, Homologous

Objective: To evaluate the safety and efficacy of chimeric antigen receptors T cells (CAR-T) in childhood acute B lymphoblastic leukemia (B-ALL) to probe the prognosis-related factors. Methods: Forty-eight children, 29 boys and 19 girls, aged 3-17years old (median age was 8 years old) , with recurrent or refractory CD19 positive B-ALL, were treated by the CD19 specific CAR-T cells. A total of 48 cases received 61 infusions. Flow cytometry or real-time quantitative polymerase chain reaction method were used to monitor micro residual disease (MRD) . The follow-up period was from 16 to 1 259 days with the median follow-up of 406 days. SPSS software was used to statistical analysis. Results: No adverse reaction was observed during 61 infusions. The most common adverse reaction after CAR-T cell infusions was cytokine-release syndrome (CRS) . Only 2 cases experienced level 3 CRS performance, including continuous high fever, convulsions, delirium, serous cavity effusion, and decreasing of blood pressure. Tocilizumab was given to release CRS performance. No treatment-related death occurred. Thirty-seven patients showed response during 7 to 28 days after infusions. The early response rate was 77.1%, with MRD before infusion less than 5% group higher than the MRD more than 5% group (87.1% vs 58.8%, χ²=4.968, P=0.036) . For the 37 patients who showed response to CAR-T cell infusions, univariate analysis identified that age, disease status at the time of treatment, MRD before infusion affected 2-year OS rate (P<0.05) . Multivariate prognostic analysis for EFS disclosed that the MRD before infusion more than 5% (RR=3.433, 95% CI 1.333-8.844, P=0.011) and not bridge to HSCT (RR=4.996, 95% CI 1.852-13.474, P=0.001) were the independent risk factors. Conclusion The fourth generation CAR-T cells directed against CD19 could effectively and safely treat relapsed and refractory B-ALL, which implicated that CAR-T therapy as a novel therapeutic approach could be useful for patients with relapsed or refractory B-ALL who have failed all other treatment options. Reducing MRD as far as possible by effective pretreatment chemotherapy was in favor of increasing the response rate. Bridging HSCT after CAR-T cell treatment might be a better therapeutic strategy for the patient with refractory or molecular relapsed B-ALL.