Targeting MUC1-C selectively inhibits growth and survival of primary AML cells. (A) Primary FLT3-ITD AML blasts from patient 4 were treated with the indicated concentrations of GO-203 for 88 hours. Cell number (mean ± SD of 3 determinations) was determined by trypan blue staining. (B) Primary FLT3-ITD blasts from patient 5 were treated with the indicated concentrations of GO-203 for 72 hours. Cell number (mean ± SD of 3 determinations) was determined by trypan blue staining. (C) Primary FLT3-WT blasts from patient 6 were treated with the indicated concentrations of GO-203 or with the control peptide, CP2, for 72 hours. Cell number (mean ± SD of 3 determinations) was determined by trypan blue staining. (D) CD34⁺ cells isolated from AML blasts (n = 4) or mobilized normal peripheral blood mononuclear cells (n = 3) were treated with 5 μM GO-203 (solid bars) or CP2 (shaded bars) each day for 3 days. The cells were then analyzed for Annexin V/PI-positive cells by flow cytometry. The results (mean ± SD for 3 independent samples) are expressed as percentage of late apoptotic/necrotic cells. (E) CD34⁺ cells isolated from AML blasts (n = 3) or mobilized normal peripheral blood mononuclear cells (n = 2) were plated in duplicate in methylcellulose in the presence of 5 μM GO-203 or CP2 for 14 days. Colony number (mean ± SD) is expressed for the indicated samples.