A phase I study of CAR-T bridging HSCT in patients with acute CD19⁺ relapse/refractory B-cell leukemia

Chimeric antigen receptor (CAR)-T cell therapy is a novel cellular immunotherapy for relapsed/refractory(R/R) B acute lymphoblastic leukemia (B-ALL). However, the survival duration of CAR-T cells in vivo is noteworthy, and in some cases recurrence occurs following CAR-T cell therapy. There is controversy over the benefits of bridging to allo-HSCT after CAR-T cell therapy. The present study explored the efficacy and safety of CD19 chimeric antigen receptor (CAR) T-bridged allogeneic hematopoietic stem cell transplantation (allo-HSCT) treatment in relapsed/refractory B-cell acute lymphocytic leukemia (R/R B-ALL). A total of 9 patients with B-ALL treated at The First Affiliated Hospital of Wenzhou Medical University between December 2016 and November 2017 were included. The results demonstrated that the total response rate on day 28 after receiving CD19-CAR T-cell therapy was 100% (9/9) and all patients exhibited complete remission. The 1-year overall survival (OS) rate for 5 patients who received CAR-T bridged HSCT was 100%, the 1-year DFS rate was 100%; the 1-year OS rate for the 4 patients who received CAR-T therapy was 75%, and the 1-year DFS rate was 75%. Patients who received CAR-T bridged to HSCT had no significant prolongation of myeloid and platelet engraftment median time compared with patients who received CAR-T alone, and the incidence of acute graft-versus-host disease or extensive chronic graft-versus-host disease did not increase. Overall, the present clinical trial demonstrated that CAR-T therapy bridging to HSCT is a feasible, safe and effective method to treat adult patients with R/R B-ALL.