Impact of the relative dose intensity on survival of patients with high-risk myelodysplastic syndromes treated with Azacitidine

We performed a retrospective analysis of 93 myelodysplastic syndromes (MDS) patients with intermediate 2 or high-risk IPSS score to study the impact of Azacitidine (AZA) relative dose intensity (RDI) <80% on the overall survival (OS). There were 51.6% of patients who had full dose and 48.4% had dose reduction or delayed with a RDI <80%. Nineteen patients (20.4%) had RDI <80% before getting objective response. Overall and progression-free survivals (OS, PFS) probabilities for the whole population were 58% (95% CI: 48-69) and 47% (95% CI: 38-58) at 1 year; 35% (95% CI: 26-47) and 31% (95% CI: 23-43) at two years, respectively. When analyzing the outcomes according to the response to AZA, median OS was 32 months (range: 26-55) for responders and 8 months (range: 7-12) for nonresponders, with a respective 1-year and 2-year OS probabilities of 91% vs 28% and 66% vs 6%, respectively (P < 0.001). Interestingly, there was no impact of dose reduction on OS nor on PFS, however, when analyzing the timing of dose reduction as time-dependent variable, we found that patients who had dose reduction before achieving the objective response, had significantly lower OS (P = 0.02) and PFS (P = 0.01) compared to patients who had dose reduction after achieving the objective response. In multivariate analysis, acute myeloid leukemia with 21%-30% blasts in BM and poor and very poor karyotype significantly impacted OS, (HR = 2.09, 95% CI: 1.27-3.44, P = 0.004, and HR = 2.73, 95% CI: 1.6-4.6, P < 0.001 respectively), as well as PFS (HR = 1.84, 95% CI: 1.07-3.17, P = 0.028, and HR = 3.03, 95% CI: 1.7-5.39, P < 0.001, respectively).