[Efficacy of CD19 Chimeric Antigen Receptors T Cells in the Treatment of Relapsed Patients with B Cell Acute Lymphoblastic Leukemia after Allogeneic Hematopoietic Stem Cell Transplantation].

Objective: To study the long-term efficacy and safety of CD19 chimeric antigen receptor T cells (CAR-T) in the treatment of relapsed patients with B-cell acute lymphoblastic leukemia (ALL) after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

Methods: A total of 7 patients with B-cell ALL relapsed after allo-HSCT were treated with CD19 CAR-T cells from September 2015 to March 2018. Among them, 6 had hematological recurrence and 1 had positive of MRD. They all were treated with a single infusion of CAR-T cells. FC chemotherapy regimen was administered before transfusion. The median number of CAR-T cells transfused was 6.0 (range 4.0-8.6) )×10/kg. Long-term efficacy and toxicity were evaluated.

Results: Bone marrow examination performed at d 30 after CAR-T infusion showed that all 7 patients achieved complete remission and MRD negative, grade I CRS for 1 case and grade II CRS for 6 cases, two of them had mild neurotoxicity, which was controlled by treatment. Two patients presented grade VI intestinal GVHD after CAR-T infusion. The median follow-up time was 18 months (range 12-42). Follow-up showed that two patients relapsed at 9 months and 14 months after treatment, out of 2 patients one died of progressive disease and the other reachived the hematological remission, but MRD was positive after CD22 CAR-T cell therapy. At present, five patients are disease-free survival, moreover showed complete donor chimerism. One year after CAR-T cell therapy, the results of immune reconstitution showed that CD4 level was more than 300×10/L in 5 patients who disease-free survived. Among them, 3 patients had poor recovery of immunoglobulin and received gamma globulin replacement therapy.

Conclusion: All patients are followed up for at least one year. The preliminary efficacy and safety are satisfactory. CAR-T cell infusion is an effective method for the treatment of B-ALL recurrence after allo-HSCT.