Early pharmacodynamic analyses of DNA hypomethylation. Shown is the hypomethylation ratio induced by decitabine in 4 different cell populations: CD34P indicates bone marrow CD34⁺ mononuclear cells (A,E,L,M); CD34N, bone marrow CD34-depleted mononuclear cells (B,F,J,N); PBMCs (C,G,K,O); and GRAN, peripheral blood granulocytes (D,H,L,P). The hypomethylation ratio is calculated as the ratio of DNA methylation detected just after completion of decitabine priming to that detected before beginning decitabine. The hypomethylation ratio is shown for all subjects (A-D), for subjects treated on each arm (E-H), at each dose level (I-L), and according to treatment response: CR, PR, or NR (M-P). Paired t test P values are indicated (NS indicates that the P value was nonsignificant).