Translational research in myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are receiving unusual attention recently as great strides have been made in understanding the biology. Recognition that excessive cytokine-induced apoptosis plays a significant role in the cytopenias of the majority of patients opened the doors to anti-cytokine therapy, with thalidomide being used with success in approximately 20% patients. Other therapies that have emerged include the thalidomide analog lenalidomide which is particularly beneficial for 5q- patients as well as a subset of non-5q- patients with low or intermediate-1 risk MDS. Other targeted therapies include vitamins, agents that are cytoprotective, differentiation inducers, anti-angiogenic, or immune modulatory. In addition, inhibitors of proteasome, methylation, histone deacetylation, farnesylation, receptor tyrosine kinases, topoisomerase, and matrix mettaloproteinases have yielded encouraging responses in subsets of patients. Specific therapies have also been developed for genetic abnormalities that lead to fusion genes (TEL-PDGFR-beta, or FIP1L1-PDGFR-alpha), or abnormal proteins due to mutations/functional inactivation (FLT3), dysregulated expression (EVI-1). In a short span of ten years, the field has evolved from having no effective therapy to offer the majority of MDS patients save chemotherapy, to having one FDA approved drug, several on the way to approval, and a number of novel agents producing exciting clinical results. This chapter summarizes the novel targets and targeted therapies in the rapidly evolving therapeutic landscape of MDS.