Optimization of transplant regimens for patients with myelodysplastic syndrome (MDS).

Myelodysplastic syndrome (MDS) is a hemopoietic stem cell disorder that is potentially curable by transplantation of normal hemopoietic stem cells. The optimum timing, however, and the best conditioning strategy have remained controversial. Both conventional and reduced-intensity/nonmyeloablative regimens have been used successfully. Among selected patients with less advanced/low-risk MDS (< 5% marrow myeloblasts), 3-year survivals of 65% to 75% are achievable with HLA-matched related and unrelated donors. Among patients with more advanced/ high-risk disease (> or = 5% marrow blasts; high International Prognostic Scoring System [IPSS] scores), the probability of post-transplant relapse ranges from 10% to 40%, and, as a result, relapse-free survival is inferior. In addition to disease stage, co-morbid conditions, pre-transplant chemotherapy, conditioning regimen, source of stem cells, and post-transplant immunosuppression affect transplant outcome. Reduced-intensity conditioning regimens are associated with a decrease in non-relapse mortality and allow for successful hemopoietic stem cell transplants even in patients 60-70 years of age. Graft-versus-host disease, both acute and chronic, and post-transplant relapse remain challenging problems.