Conditioning Regimens for Stem Cell Transplantion in MDS

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Improving outcomes for individuals with myelodysplastic syndrome (MDS) is a big challenge, states Thomas Prebet, MD, PhD. Stem cell transplantation should be considered for all patients, especially those with high-risk disease. However, strong evidence is lacking insofar as which pretransplant regimen—hypomethylating agents or induction chemotherapy—is preferable.

Hypomethylating agents may yield better results than induction chemotherapy in individuals with poor MDS cytogenetics, says Prebet. However, induction chemotherapy may be associated with more marrow remission. Moreover, induction chemotherapy requires hospitalization and may cause more morbidity and mortality, but this regimen is faster than a hypomethylating agent.

Individuals with MDS are usually older adults, explains Prebet, and the use of myeloablative conditioning is more complicated for these patients. The majority of MDS cases are treated with reduced intensity conditioning, which may appeal to a larger population. However, without the myeloablative effect, there is a slight increase in relapse rates with reduced intensity conditioning compared with myeloablative conditioning.

Additional conditioning options include the use of reduced toxicity conditioning, which could be considered to be in the middle of the treatment continuum, between reduced intensity and myeloablative conditioning. Preemptive treatment after transplant may help prevent relapse. A common method involves the use of hypomethylating agents, which are thought to have an impact in individuals with the highest risk of relapse.