The primary registration trials used for the approval of epoetin alfa demonstrated correction of anemia and virtual elimination of transfusions (>90% reduction) in patients treated with ESAs to a mean hemoglobin (Hb) of 11.7 g/dL (within the target range of 10.7 to 12.7 g/dL) [7]. This evidence concerns the gene GSTM1 and anemia (phenotype).