Antileukemic effects of cercosporamide on primary leukemic progenitors from AML patients. (A) Dose-dependent suppression of primitive leukemic precursors from AML patients by cercosporamide. Effects were assessed in clonogenic assays in methylcellulose. Data are expressed as percentage control of leukemic colonies for untreated cells and represent means ± SE of 3 experiments, using cells from 3 different patients. (B) Effects of the combination of rapamycin (20 nM) and cercosporamide (1 µM) on primitive leukemic precursors from AML patients. Leukemic CFU-L colony formation was assessed in clonogenic assays in methylcellulose. Data are expressed as percentage control of leukemic colonies for untreated cells and represent means ± SE of 4 experiments, using cells from 4 different patients. Paired t test analysis of the combination of rapamycin and cercosporamide showed P = .0188 compared with rapamycin alone and P = .0125 compared with cercosporamide alone. (C) Effects of the combination of Ara-C (1 ng/ml) and cercosporamide (1 µM) on primitive leukemic precursors from AML patients. Leukemic CFU-L colony formation was assessed in clonogenic assays in methylcellulose. Data are expressed as percentage control of leukemic colonies for untreated cells and represent means ± SE of 4 experiments. Paired t test analysis of the combination of Ara-C and cercosporamide showed P = .0013 compared with Ara-C alone and P = .0193 compared with cercosporamide alone.