The outcome of patients with high-risk MDS achieving stable disease after treatment with 5-azacytidine: A retrospective analysis of the Hellenic (Greek) MDS Study Group.

The demethylating factor 5-azacytidine (5-AZA) improves survival in intermediate-2 and high-risk myelodysplastic syndrome (MDS) patients [according to the International Prognostic Score System (IPSS)] responding to treatment. However, the outcome of patients achieving stable disease (SD) is unclear. This retrospective study of the Hellenic MDS Study Group included 353 intermediate-2 or high IPSS risk patients treated with 5-AZA. Forty-four out of 86 (51.6%) patients achieving SD and continuing treatment with 5-AZA showed a lower risk of transformation of MDS to acute myeloid leukemia (AML) and increased overall survival (OS), compared to SD patients who discontinued the treatment (estimated median AML-free survival = 38 months, 95% CI = 10.7-65.3 vs 15 months, 95% CI = 10.4-19.6, P < .001; estimated median OS = 20 months, 95% CI = 5.5-34.5 vs 11 months, 95% CI = 5.8-16.2, P < .001). Moreover, SD patients continuing treatment with 5-AZA had no differences in AML-free survival compared to patients showing response to 5-AZA (estimated median AML-free survival = 38 months, 95% CI = 10.7-65.3 vs 31 months, 95% CI = 23.6-38.4, P = .45; estimated median OS 20 months, 95% CI = 5.5-34.5 vs 25 months, 95% CI = 21.3-28.7, P = .50). In conclusion, MDS patients achieving SD in the first 6 months of treatment with 5-AZA as best response should continue receiving 5-AZA as they may benefit from prolonged treatment.