“…Morphologically, elderly blasts have less granulation and fewer Auer rods (Hassan & Rees, 1990), and biologically, elderly AML has a more immature stem cell-like phenotype (Fialkow et al, 1981), resulting in increased cytopenias and toxicity with treatment (Stephan et al, 1998). Elderly patients have overexpression of the multidrug resistance 1 (MDR1) gene (Leith et al, 1997(Leith et al, , 1999Appelbaum et al, 2006;Roboz, 2007;Sekeres, 2008;Kuendgen & Germing, 2009), which encodes an efflux pump, permeability glycoprotein (Pgp), that extrudes chemotherapeutics from the cell and increases treatment resistance (Leith et al, 1997;van der Kolk et al, 2002;Larson, 2003;Solary et al, 2003;Mahadevan & List, 2004;Burnett & Mohite, 2006). MDR1 over-expression correlates with a reduced CR rate, OS and DFS, and is associated with relapsed and refractory disease, secondary AML and adverse cytogenetics (Wood et al, 1994;Willman, 1996;Leith et al, 1999;Pinto et al, 2001;Baer et al, 2002;Larson, 2003;van der Holt et al, 2005;Burnett & Mohite, 2006;Estey, 2007;Dombret et al, 2008).…”