Transplantation for myelodysplastic syndromes: who, when, and which conditioning regimens

Allogeneic hematopoietic stem cell transplantation (HCT) is the only curative therapy for myelodysplastic syndrome (MDS). Broad application is hindered by high risks of transplant-related morbidity and mortality, especially in the older age range represented by the MDS population. However, recent advances in strategies to minimize regimen-related toxicity make HCT a viable option for many more patients. Appropriate selection of patients involves consideration of patient factors, including use of geriatric assessment tools and comorbidity scales, that predict risks of regimen-related toxicity as well as disease factors, including genetic markers, which predict survival with both non-HCT and HCT therapy. Optimal timing of HCT for fit patients must consider MDS risk scores and life-years to be gained, with earlier transplantation indicated for patients with intermediate-2 and high-risk disease but judicious delay for lower risk patients. Selection of suitable conditioning regimens must balance risks of toxicity with opportunity for maximum disease control.