Hematopoietic cell transplantation for patients with myelodysplastic syndromes (MDS): when, how and for whom?

Hematopoietic cell transplantation (HCT) offers potentially curative therapy for patients with myelodysplastic syndromes (MDS). However, who should and can be transplanted, with which approach, and when is a matter of debate. Various classification schemes and prognostic scoring systems have helped in the decision-making process. Offering HCT to patients who were not considered transplant candidates in the past is now possible with the development of new transplant strategies. In addition to disease stage, patient age, comorbid conditions, preHCT chemotherapy, type of donor, source of stem cells, and possibly other factors, need to be considered prior to transplant. Patients without substantial comorbid conditions up to 60 years with the availability of unrelated donor grafts or 65 years with related donor grafts can be transplanted with more conventional (higher dose) regimens (e.g. targeted BU/CY; Flu/BU). Older patients and patients with comorbid conditions should be enrolled in trials aimed at optimizing RIC/nonmyeloablative HCT (e.g. Flu/melphalan; Flu/low dose TBI). Patients who present with 'advanced' MDS or are transfusion dependent, and do not have a del(5q), should probably be transplanted early in their course. GVHD (in all patients) and post-HCT relapse (in patients with high risk disease) remain major problems. Modifications of transplant conditioning regimens have reduced transplant-related mortality and allow successful HCT even in older patients. However, prospective randomized trials are needed to determine the role of pre-HCT chemotherapy and the type of transplant conditioning regimen best suited for a given patient.