Standard dose and prolonged administration of azacitidine are associated with improved efficacy in a real-world group of patients with myelodysplastic syndrome or low blast count acute myeloid leukemia.

Objective: Azacitidine is the standard of care for higher-risk myelodysplastic syndromes (MDS). We evaluated factors affecting the outcome of azacitidine treatment in 196 'real-world' patients, retrospectively collected by two Italian cooperative groups.

Methods: The study included 184 MDS and 12 low blast count acute myeloid leukemia (AML). Azacitidine was administered at the standard dose of 75 mg/m(2)/d for 7 d (SD) in 163 patients and 100 mg/d for 5-7 d in 33 patients.

Results: After a median of 4.5 azacitidine cycles (range 7-15 cycles), 182 patients were evaluable for response. Nineteen percent achieved complete remission (CR), 17% partial remission (PR), and 21% hematological improvement (HI). The disease was stable or progressive in 29% and 14% of patients, respectively. The probability of response was significantly higher in patients who received the 75 mg/m(2)/7 d compared with 100 mg through 5-7 d dose (CR/PR/HI: 63 vs. 29%, P = 0.0005). Median overall survival was 17.1 months. Low MDS-CI and achievement of CR/PR/HI were significant predictors of survival in the multivariable analysis.

Conclusions: Our data show that maximal azacitidine efficacy is associated with the standard dose and with prolonged treatment, beyond 4-6 cycles, with the goal of also improving the 'quality' of response. Lower MDS-CI and IPSS-R scores, hematologic response and disease stability, are associated with longer survival. The risk of febrile events is highest during the first treatment cycles and is associated with active disease.