Immunosuppressive Therapy for Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) comprise a heterogeneous group of diseases characterized by bone marrow failure, marrow dysplasia, and a tendency to evolve to acute leukemia. Pathophysiologically, low risk MDS are separated from the high risk category by an increased rate of apoptosis of the bone marrow cells which causes the morphological paradoxon of a peripheral cytopenia and hypercellular bone marrow known as ineffective hematopoesis. Laboratory findings and clinical evidence suggest that some patients with myelodysplastic syndrome have immunologically mediated disease. MDS shares some of the features of acquired aplastic anemia and up to 30% of patients with MDS respond to immunosuppressive treatment. In the last decades, significant advances have been made in the diagnostic and prognostic classifications of myelodysplastic syndromes. While allogeneic transplantation still offers the only available option with a probability of cure in a minority of patients, the mainstay of therapy in low-risk patients remains supportive care, stimulation of ineffective hematopoiesis with growth factors, and immunomodulatory therapy. However, the correct selection of patients for the respective therapeutic intervention continues to be an enormous challenge as this will decide about the probability of therapeutic efficacy. This is important not only because of the high costs involved but also because of the possible side effects that can be difficult to manage. Here we review the pathophysiologic basis for the use of immunosuppressive agents in MDS and summarize the trials leading to the establishment of these therapy strategies in a subgroup of low-risk MDS patients.