Different Clinical Results with the Use of Different Dosing Schedules of Azacitidine in Patients with Myelodysplastic Syndrome Managed in Community-Based Practice: Effectiveness and Safety Data From the Spanish Azacitidine Compassionate Use Registry.

Azacitidine (AZA), a hypomethylating agent recently approved in Europe for the treatment of myelodysplastic syndrome (MDS), prolongs the median survival time in patients enrolled in clinical trials (Fenaux et al 2009). AZA was available for clinical trial or compassionate use in Spain before receiving its marketing authorization from the Spanish Medicines Agency in May 2009. The dosing of AZA in community-based hematology clinics could differ from that approved by the health authorities.

We present the preliminary analysis of the clinical results of data from a longitudinal, multicenter Spanish patient registry, which retrospectively collected data from community-based hematology clinics on the disease course and management of patients with MDS treated under compassionate use conditions with AZA, in whom the dosing schedule administered was documented. AZA was administered to the patients in three different dosing schedules over 28-day cycles; Group A: days 1, 2, 3, 4 and 5 / Group B: days 1, 2, 3, 4, 5, 8 and 9 / Group C: days 1, 2, 3, 4, 5, 6, 7. Treatment assignation was based on patient status and the feasibility of weekend drug administration. As of August 1, 2009, data from 147 patients with MDS diagnosed according to the WHO criteria had been collected.

We evaluated 144 patients in whom the dosing schedule was documented at the time of this analysis. At baseline, the patient characteristics were comparable, except for ECOG performance status, with a higher prevalence of an ECOG ≥ 2 in the day 1-7 dosing schedule group (Group C) (Table 1). Group A accounted for 36% of the patients, group B for 32%, and group C for 32%. The mean initial dose of AZA was comparable between groups. Despite the different dosing schedules, the median number of cycles administered was similar between groups. The overall treatment response rates (International Working Group 2006 criteria) varied according to dosing schedule: 58% in group A, 65% in group B and 74% group C (Table 1). AZA was generally well tolerated, but the adverse events profile differed according to dosing schedule group (Table 1)

Our results demonstrate that different treatment schemes are feasible for patients with MDS treated with AZA in the community-based setting, but they have different effectiveness and the safety profiles. These data show a better efficacy/safety profile for the dosing schedule approved by the EMEA. Further analyses are awaited.

No relevant conflicts of interest to declare.