Azacitidine or 5-azacytidine, sold under the trade name Vidaza, is a chemical analogue of cytidine, a nucleoside present in DNA and RNA. Azacitidine and its deoxy derivative, decitabine (also known as 5-aza-2′deoxycytidine), are used in the treatment of myelodysplastic syndrome. Both drugs were first synthesized in Czechoslovakia as potential chemotherapeutic agents for cancer. Azacitidine has also been used as an experimental treatment in clinical trials involving cases of acute myeloid leukemia, where the patient has suffered more than one relapse- in these cases, standard chemotherapy, hematopoietic stem cell transplantation, and other mainline treatments have failed.