VX-680 inhibits activation of Aur-A and causes apoptotic cell death in AML blasts but not in normal BMMCs. (A) VX-680 induces primary leukemic blast apoptosis in a dose-dependent manner. Blasts from 98 AML patients and 12 normal donors were incubated with VX-680 as indicated doses for 72 hours. The apoptosis was assessed by annexin V assays. Mean percentage of apoptosis was shown (P < .001). (B) VX-680 inhibits autophosphorylation of Aur-A at Thr288 in primary leukemia cells. Cells from patient 11 were incubated with increasing amounts of VX-680 or DMSO for 24 hours. Cell lysates were subject to Western blot analysis with phospho-Aur-A (Thr288) antibody. (C) VX-680 induces cleavage of PARP. Blasts from patient 11 (> 90% blasts) were treated with VX-680 with indicated doses for 72 hours before analysis of PARP cleavage by Western blot. GAPDH levels represent loading controls. (D) Cells from patient 11 (top panel) and normal donor 1 (bottom panel) were incubated for 72 hours with indicated doses of VX-680 before staining with annexin V-FITC and PI. The percentages of apoptotic cells were displayed.