Comparison of Allo-HSCT outcomes after CAR-T therapy versus chemotherapy in pediatric patients with relapsed/refractory B-ALL: a retrospective study

Background Hematopoietic stem cell transplantation (HSCT) is a curable treatment for refractory/relapse B-cell acute lymphoblastic leukemia (R/R B-ALL).Traditional chemotherapy or Chimeric antigen receptor T-cell (CAR-T) therapy are both important methods to achieve MRD negativity before HSCT. However, which treatment is preferred needs to be clarified. Patients and Methods In this study, 269 patient s with R/R B-ALL who underwent allo-HSCT after CAR-T cell therapy (CAR-T, n = 142) or chemotherapy (CT, n = 127) were enrolled from multicenters. Results The 3-year overall survival (OS) after transplantation was 66.8% in the CAR-T group and 72.3% in the chemotherapy (CT) group. The 3-year relapse-free survival (RFS) was 65.3% in the CAR-T group and 65.9% in the CT group. The 3-year graft-versus-host disease, relapse-free survival (GRFS) and cumulative incidence of relapse (CIR) were also similar between the two groups. Among patients who achieved first complete remission (CR1) before transplantation, the proportion receiving chemotherapy was significantly higher than that receiving CAR-T therapy (37.5% vs. 13.6%; P < 0.001). In this CR1 subgroup, the CT group demonstrated superior outcomes, including improved OS, RFS, and GRFS. Conclusion In pediatric R/R B-ALL, CAR-T bridging to HSCT appears to yield post-transplant survival comparable to chemotherapy, though a higher rate of moderate to severe chronic GVHD was observed. CAR-T may be a reasonable option, but closer GVHD monitoring seems warranted.