Prospective Comparison of Azacitidine Treatment between 7-Days and 5-Days Schedules for Patients with Higher-Risk Myelodysplastic Syndromes; Results of Japan Adult Leukemia Study Group MDS212 Trial

▪ Background Azacitidine (AZA) is one of the hypomethylating agents (HMAs) proven to significantly prolong overall survival (OS) for patients with higher-risk myelodysplastic syndromes (h-MDS) via a prospective phase 3 trial. However, the optimal treatment schedule of AZA for h-MDS has not yet been prospectively determined. As a 7-day treatment schedule includes weekends, a 5-day administration has also been applied with h-MDS, though solid evidence has not been established. Based on this background, we planned to compare AZA treatment on 7-day and 5-day schedules. Patients Patients diagnosed with de novo or treatment-related MDS (FAB-defined RAEB and RAEB-t), aged 16 years or older were eligible for this study, if they showed adequate performance status (ECOG PS 0-2) and no history of HMA treatment or chemotherapy. Candidates for allogeneic stem-cell transplantation were excluded. Study design This was a multicenter, randomized, open-label, phase 3 trial to compare the efficacy of AZA treatment for 7-days (AZA-7) to 5-days (AZA-5). The primary endpoint was 2-year OS rate (2y OS). AZA was given subcutaneously at 75 mg/m² every 28 days. To test the non-inferiority of AZA-5 to AZA-7, 2y OS of AZA-7 was estimated at 30%, and the delta was defined as 11%, for which 410 patients were needed to complete the trial. However, because of the poor recruitment, this study closed prematurely, and the protocol-planned interim analysis (when 200 patients were registered) was performed. This protocol was approved by the IRB at each trial center. All patients provided written informed consent, and the trial was conducted in accordance with the Declaration of Helsinki. The efficacy of AZA was evaluated using IWG2006 criteria, and treatment was continued until study completion, or relapse, unacceptable toxicity, or disease progression was observed. Efficacy was analyzed by intention-to-treat. Secondary endpoints were the hematological response rate, 2-year leukemia-free survival (2y LFS) rate, the cytogenetic response, and occurrence of adverse events. Results Between January 2013 and Jun 2018, 201 patients were randomly assigned to AZA-7 (n=99) or AZA-5 group (n=102). The median age of all patients at the enrollment was 73.5 years old (range, 48 to 91). Between the two groups, there was no significant difference in the baseline characteristics, such as sex, type of MDS (de novo or treatment-related), percent of BM blasts, FAB and WHO classification, and IPSS and IPSS-R risk