Allogeneic hematopoietic stem cell transplantation with reduced-intensity conditioning in acute lymphoblastic leukemia: a feasibility study

Abstract

BACKGROUND AND OBJECTIVES: Numerous studies have reported the feasibility of performing allogeneic hematopoietic stem cell transplantation with reduced-intensity conditioning, although results in individual diseases are scarce, with no studies in patients with acute lymphoblastic leukemia (ALL). We sought to analyze the results of reduced intensity conditioning for allografts in adult patients with ALL. DESIGN AND METHODS: We report the results of a reduced intensity conditioning regimen followed by allogeneic hematopoietic stem cell transplantation in 27 adult patients with high-risk ALL who were included in four prospective studies. RESULTS: The median age was 50 years; 23 (85%) patients were beyond first complete remission, 44% were chemorefractory and 41% were Philadelphia chromosome positive. Donors were mismatched related donors or volunteer unrelated donors in 12 cases (44%). The incidence of grades II-IV acute graft-versus-host disease (GVHD) was 48%, and 13 of 18 evaluable patients (72%) developed chronic GVHD. Currently nine patients are alive, with a median follow-up of 809 days (range, 381-1375). The 2-year incidence of transplant-related mortality was 23% (95% CI, 11% to 46%), and the 2-year probability of overall survival was 31% (95% CI, 12 to 48%), while the 2-year incidence of disease progression was 49% (95% CI, 33% to 72%). The 2-year incidence of disease progression in patients with and without GVHD was 35% (95% CI, 19% to 57%) and 70% (95% CI, 47% to 100%), respectively (p=0.05). INTERPRETATION AND CONCLUSIONS: This retrospective study suggests that allogeneic hematopoietic stem cell transplantation with reduced intensity conditioning might be a useful therapeutic option for some patients with ALL who are ineligible for standard myeloablative conditioning. However, this treatment modality needs to be evaluated in prospective trials, and should not be employed outside clinical studies.