Retrospective comparison of reduced-intensity conditioning and conventional high-dose conditioning for allogeneic hematopoietic stem cell transplantation using HLA-identical sibling donors in myelodysplastic syndromes

In this multicenter retrospective study, the outcomes of 836 patients with myelodysplastic syndrome (MDS) who underwent transplantation with a human leukocyte antigen (HLA)–identical sibling donor were analyzed according to 2 types of conditioning: reduced-intensity conditioning (RIC) in 215 patients, and standard myeloablative (or high-dose) conditioning (SMC) in 621 patients. In multivariate analysis, the 3-year relapse rate was significantly increased after RIC (hazard ratio [HR], 1.64; 95% confidence interval [95% CI], 1.2-2.2; P= .001), but the 3-year nonrelapse mortality (NRM) rate was decreased in the RIC group (HR, 0.61; 95% CI, 0.41-0.91; P= .015). The 3-year probabilities of progression-free and overall survivals were similar in both groups (39% after SMC vs 33% in RIC; multivariate P= .9; and 45% vs 41%, respectively; P= .8). In conclusion, the lower 3-year NRM after RIC is encouraging, since these patients were older (age > 50 years in 73% RIC vs 28% in SMC, P< .001) and had more adverse pretransplantation variables. However, based on the higher risk of relapse, patients with no contraindications for SMC should not receive RIC outside of prospective randomized trials, which are needed to establish the position of RIC-based transplantation in the treatment of patients with MDS.