DNMT1 and myelodysplastic syndrome: Hypermethylation of tumor suppressor genes or hypomethylation of oncogenic loci represent attractive targets for therapeutic approaches via targeting DNMTs or histone-modifying enzymes.167,168 Azacitidine and 5-aza-2’-deoxycytidine (decitabine) are clinically approved DNMT inhibitors that improved the treatment of myelodysplastic syndrome (MDS), chronic myelomonocytic leukemia (CMML) and AML.169,170 Several compounds have been applied in clinical studies as single agents, but also in combinations with small molecule inhibitors or chemotherapy.