GSTM1 and anemia (phenotype): In univariate analysis, pre-treatment factors negatively correlating with spleen response were: IPSS risk intermediate-2/high (p=0.001), spleen palpable ≥10 cm below LCM (p=0.001), transfusion-dependency (p=0.001), time interval between MF diagnosis and RUX start >2 years (p=0.011), anemia (Hb <10 g/dl, p=0.005), grade 3 marrow fibrosis (p=0.004), platelet count <200×109/l (p=0.002), and RUX starting dose <20 mg BID (p=0.001) (Figure 3A).