Allogeneic Hematopoietic Stem Cell Transplantation, Especially Haploidentical, May Improve Long-Term Survival for Children with High-Risk T-Cell Acute Lymphoblastic Leukemia in First Complete Remission

Abstract

Background: The role of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for children with high-risk (HR) T- cell acute lymphoblastic leukemia (T-ALL) in first complete remission (CR1) is still under critical discussion. Moreover, relapse is still the main factor affecting survival. This study explored the effect of allo-HSCT (especially haploidentical HSCT (haplo-HSCT) ) on improving survival and reducing relapse for children with HR T-ALL in CR1 and the prognostic factors of childhood T-ALL in order to identify who could benefit from HSCT.Methods: Seventy-four newly diagnosed pediatric T-ALL patients were included in this study and stratified into low-risk chemotherapy cohort (n=16), high-risk chemotherapy cohort (n=31) and high-risk transplant cohort (n=27). The characteristics, survival outcomes and prognostic factors of all patients were analyzed.Results: Patient prognosis in the high-risk chemotherapy cohort was significantly inferior to the low-risk chemotherapy cohort (5-year overall survival (OS): 51.2%±10% vs. 100%, P = 0.003; 5-year event-free survival (EFS): 48.4%±9.8% vs. 93.8%±6.1%, P = 0.01; 5-year cumulative incidence of relapse (CIR): 45.5%±0.8% vs. 6.3%±0.4%, P = 0.043). For high-risk patients, allo-HSCT could improve the 5-year EFS and CIR compared to chemotherapy (5-year EFS: 77.0%±8.3% vs. 48.4%±9.8%, P = 0.041; 5-year CIR: 11.9%±0.4% vs. 45.5%±0.8%, P = 0.011). 5-year OS in high-risk transplant cohort had a trend for better than that in high-risk chemotherapy cohort ( 77.0%±8.3% vs. 51.2%±10%, P = 0.084). Haplo-HSCT could reduce relapse and had a trend for improving long-term survival for HR patients when compared to the high-risk chemotherapy cohort (5-year OS: 80.0%±8.9% vs. 51.2%±10%, P = 0.093; 5-year EFS: 80.0%±8.9% vs. 48.4%±9.8%, P = 0.047; 5-year CIR: 13.9%±0.6% vs. 45.5%±0.8%, P = 0.022). Minimal residual disease (MRD) re-emergence was the independent risk factor associated with 5-year OS, EFS and CIR.Conclusions: allo-HSCT, especially haplo-HSCT, might effectively improve the survival outcomes for HR childhood T-ALL in CR1.