Clofarabine/busulfan-based reduced intensity conditioning regimens provides very good survivals in acute myeloid leukemia patients in complete remission at transplant: a retrospective study on behalf of the SFGM-TC

Abstract

Background: Clofarabine has been proved to have higher anti-leukemic myeloid activity compared to fludarabine, a drug extensively used as part of reduced intensity conditioning ({RIC}) for allogeneic stem cell transplantation (allo-{SCT}). Results: Eighty-four patients were included. The majority of patients had acute myeloid leukemia ({AML}, n = 63). Sixty-one patients were in complete remission ({AML} n = 55). With a median follow up of 31 months (range: 5.7-74.1), 2-year overall ({OS}) and disease-free ({DFS}) survivals, relapse incidence ({RI}), non-relapse mortality ({NRM}) and graft-versus-host disease ({GVHD})/relapse free survival ({GRFS}) were 64.5% (53.8-75.2); 57.2% (46.2-68.2); 27.7% (18.2-37.9); 15.1% (8.2-23.9) and 43.6% (32.5-54.7), respectively. Considering {AML} in remission, 2-year {OS}, {DFS}, {RI}, {NRM} and {GRFS} were 74.2% (62-86.5); 66.8% (53.6-79.9); 23.4% (12.7-36); 9.8% (3.5-19.9) and 50.9% (36.9-64.9), respectively. Two-year outcomes were similar between {CloB}2A1 and {CloB}2A2 sub-groups. In multivariate analysis, active disease at transplant was the only factor adversely impacting 2 years outcomes. Conclusions: {CloB}2A2/A1 {RIC} regimen provides very good results for {AML} patients allografted in {CR} and could be retained as a new {RIC} platform for these patients. Materials and Methods: This was a retrospective study including all patients who received a clofarabine/busulfan based {RIC} allo-{SCT} for myeloid malignancies and reported within the {SFGM}-{TC} registry. {RIC} regimen consisted of clofarabine 30 mg/m2/day 4 to 5 days (Clo), busulfan 3.2 mg/kg/day 2 days (B2) and 2.5 mg/kg/day of rabbit anti-thymocyte globulin 1 or 2 days (A1 or A2). The primary objective of the study was to report the main outcomes of the whole cohort at 2 years.