Superior Survival of Unmanipulated Haploidentical Hematopoietic Stem Cell Transplantation Compared with Chemotherapy Alone Used as Post-Remission Therapy in Adults with Standard-Risk Acute Lymphoblastic Leukemia in First Complete Remission

Abstract

We wanted to compare the efficacy of haploidentical hematopoietic stem cell transplantation (HSCT) with chemotherapy alone in adults with standard-risk acute lymphoblastic leukemia (ALL) in first complete remission (CR1). One hundred thirty-eight consecutive adult patients with standard-risk ALL in CR1 were retrospectively investigated. Of these patients, 59 received chemotherapy alone (group A) and 79 received unmanipulated haploidentical HSCT (group B). Cumulative incidence of relapse at 5 years in group A was significantly higher than that in group B (66.3% versus 29.9%, P < .0001). Overall and disease-free survival in group A were significantly inferior to group B (P < .0001). Moreover, multivariate analyses demonstrated that central nervous system leukemia (P = .002), T cell immunophenotype (P = .044), expression of E2A-PBX1 (P = .007), and positive minimal residual disease after the first cycle of consolidation (P = .004) were correlated with relapse. Patients with 1 of 4 risk factors were assigned to the high-risk group. Otherwise, patients without risk factors were assigned to the low-risk group. In the high-risk group, HSCT had lower relapse rates and superior DFS compared with chemotherapy (P < .05), but in the low-risk group, there were no differences between HSCT and chemotherapy (P > .05). This study is the first to demonstrate that compared with chemotherapy alone, haploidentical HSCT is a better postremission therapy in adults with standard-risk ALL in CR1. Moreover, based on the 4 risk factors, the establishment of risk stratification could identify the subgroup of patients with a higher risk of relapse in adults with standard-risk ALL in CR1. Furthermore, risk stratification–directed postremission therapies using haploidentical HSCT or chemotherapy alone not only reduce relapse rate but also avoid unnecessary treatment-related mortality and improve survival.