Myeloablative versus Reduced-Intensity Conditioning in Patients with Myeloid Malignancies: A Propensity Score-Matched Analysis

•Reduced-intensity conditioning is comparable to myeloablative conditioning before allogeneic hematopoietic stem cell transplantation for acute myelogenous leukemia/myelodysplastic syndrome.•Propensity score matching analysis balances pretransplantation patient characteristics.•Addition of low-dose total body irradiation to allogeneic hematopoietic stem cell transplantation conditioning could reduce the risk of relapse.

Reduced-intensity conditioning (RIC) has been shown to have similar overall survival (OS) but higher relapse rates compared with myeloablative (MAC) regimens in patients with myeloid malignancies undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Using propensity score matching (PSM) analysis, well-balanced pairs of different variables can be compared effectively. We retrospectively compared allo-HSCT recipients with acute myeloid leukemia or myelodysplasia receiving a RIC regimen (FBT200; fludarabine 30 mg/m2/day for 4 days, busulfan 3.2 mg/kg/day for 2 days, and total body irradiation [TBI] 200 cGy) or MAC regimen (FBT400; fludarabine 50 mg/m2/day for 4 days, busulfan 3.2 mg/kg/day for 4 days, and TBI 400 cGy). A total of 248 patients (121 in the RIC group and 127 in the MAC group) were included in the analysis. No statistically significant difference was observed in 2-year OS (RIC group, 45.2 ± 5.0%; MAC group, 51.7 ± 5.2%; P = .541), nonrelapse mortality (NRM; RIC group, 28.7 ± 2.8% MAC group, 34.7 ± 4.6%; P = .368), and acute graft-versus-host disease (GVHD) (P = .171) or chronic GVHD (P = .605) at 1 year. The cumulative incidence of relapse (CIR) at 2 years was statistically significantly different between the 2 groups, however (RIC, 26.1 ± 2.6%; MAC, 14.2 ± 3.5%; P = .033). When PSM was applied to the study population, 42 case-control pairs were evenly matched. PSM analysis confirmed no statistically significant difference in 2-year OS (RIC, 49.0 ± 9.1%; MAC, 54.9 ± 7.7%; P = .718), NRM (RIC, 22.2 ± 2.3%; MAC, 33.3 ± 2.8%; P = .238), or CIR (RIC, 25.7 ± 2.6%; MAC, 9.5 ± 1.1%; P = .315) in the PSM pairs. Our findings demonstrate that after applying PSM, FBT 200 RIC conditioning has comparable OS, NRM, and CIR to FBT 400 MAC conditioning before allo-HSCT.