Comparision of efficacy and hematologic toxicity of DNA methyl transferase inhibitors in patients with myelodysplastic syndrome

The aim of this retrospective study is to compare the efficacy, overall survival, time to AML transformation, hematological toxicity and transfusion requirement of azacitidine and decitabine in patients with MDS RAEB-1 and RAEB-2. A total of 51 patients over the age of 18, diagnosed as MDS RAEB-1 and RAEB-2 treated with azacitidine and decitabine in various hematology sections of hospitals were evaluated respectively. The primary end point of the study was time to AML transformation at the end of the 12 months. The second end points were overall survival, response to treatment, transfusion requirement, febril neutropenia frequency and the antifungal treatment necessity during the treatment period. Response to treatment was classified according to International Working Group response criterias. There was no significant difference between the groups in terms of age, gender, performance score, diagnosis, etiology, treatment cycles, bone marrow cellularity and blast percentage. The most of the patients received at least 4 courses of both azacitidine and decitabine. There was no significant difference in overall survival between the azacitidine and decitabine groups (p= 0.55). Likewise, there was no difference in red blood cell and platelet transfusion requirement and febril neutropenia frequency (p = 0.46, p = 0.27, p = 0.19). The median follow- up duration of patients was 31 months for azacitidine and 20 months for decitabine; the 12 months overall survival rates did not differ significantly between the groups (p = 0,15). 1 year incidence of transformation to AML was %26 in azacitidine group and %33 in decitabine group. This rate may seen higher in decitabine group, but the difference was not statistically significant (p= 0.55). In conclusion both azacitidine and decitabine regimens were effective in the treatment of patients with MDS RAEB-1 and RAEB-2, and there was no significant difference between the treatments in terms of response rates, overall survival, leukemic transformation and hematologic toxicity. Studies including high risk MDS patients and subgroup analysis, would be useful to compare the efficacy and the side effect profile of these two similar agents Key words: MDS RAEB-1, MDS RAEB-2, Azacitidine, Decitabine