Systematic review of azacitidine regimens in myelodysplastic syndrome and acute myeloid leukemia.

Background: 5-Azacitidine administered as a 7-day dosing regimen (7-0-0) is approved in high risk IPSS myelodysplastic syndrome (MDS) patients. Alternative regimens such as a 5-day (5-0-0) or 7-day with a weekend break (5-2-2) are commonly used. No randomized controlled trial has been done directly comparing all three dosing regimens. The objective of this study was to compare the efficacies of the 5-0-0, 5-2-2, and 7-0-0 regimens in MDS and AML.

Methods: A systematic review was conducted using MEDLINE, EMBASE and CENTRAL. Eligible studies were randomized controlled trials (RCTs), observational prospective and retrospective studies. The primary clinical outcomes were Objective Response Rate (ORR) defined as the sum of complete response (CR), partial response (PR), and hematological improvement (HI) as defined by the IWG 2006 criteria. A meta-analysis of simple proportions was conducted using a random effects model with weights defined according to Laird and Mosteller. Comparisons between groups were not attempted due to the heterogeneity of study designs.

Results: The only RCT directly comparing alternative azacitidine regimens showed no difference in ORR between the 5-0-0 and 5-2-2 regimens. All other RCTs compared a dosing regimen to conventional care. The pooled proportion of ORR was 44.8% with 95% CI (42.8%, 45.5%) for 7-0-0, 41.2% with 95% CI (39.2%, 41.9%) for 5-0-0, and 45.8% with 95% CI (42.6%, 46.4%) for 5-2-2.

Conclusions: Indirect comparison of alternative azacitidine dosing regimens in MDS and AML shows a benefit for the 7-day regimen in attaining ORR. Additional RCTs are required to definitively address this comparison.