Comparing the Results of Non-TBI Hematopoietic Stem Cell Transplantation in Pediatric Patients with Acute Lymphoblastic Leukemia (ALL) with and without CNS Involvement

Introduction: There are limited data on the impact of hematopoietic stem cell transplant (HSCT) conditioning regimen, especially without total body radiation (TBI) in pediatric patients with acute lymphoblastic leukemia (ALL) with central nervous system (CNS) involvement. The aim of this study is compare the results of HSCT using non-TBI conditioning regimen in ALL patients aged ≤18 years with or without CNS involvement.

Patients and methods: Records of 183 patients with ALL (128male; 55female) with a median age of 14.1±3.7years who had undergone HSCT was studied and classified in two groups: with and without CNS involvement. Long-term consequence of the HSCT consisting of leukemia free survival (LFS), the overall survival (OS), relapse and transplant-related mortality (TRM) were compared in the two groups.

Results: A total of 183 ALL patients (148 without CNS involvement and 35 with CNS involvement) underwent HSCT in our center using a TBI-free conditioning containing Busulfan and Cyclophosphomide. The median time of follow up was 42.1 months. Estimated probability on relapse at 4 year was 51.4% in patients with CNS involvement and 42.1% in patients without CNS involvement (p=0.588). Regarding survival analysis, 4-year OS and LFS in all patients was 44.4% (SE:2.5%) and 39.7%(SE:2.5%). In multivariate analysis there were no significant differences in OS and LFS between two groups (p=0.839, p=894) nor there was a difference in relapse probability (HR:1.20, 95%CI:0.69-2.1, p=0.513) and TRM (HR:0.44, 95%CI:0.10-1.92, p=0.286).

Conclusion: HSCT using a non TBI conditioning regimen in ALL are similar with studies using TBI containing regimens. Furthermore HSCT lead to similar clinical outcomes and long-term survival in the ALL pediatric patients with or without CNS involvement.