TAK-981’s activity against primary AML cells ex vivo. Freshly isolated mononuclear cells from BM of 13 patients with AML were cultured with different doses of TAK-981, cytarabine, or both for 48 hours. Leukemic cells were gated with CD33 and/or CD34 by flow cytometry and viable cells (4′,6-diamidino-2-phenylindole [DAPI]–negative/Annexin V–negative) were compared between groups. (A) Potency and combination effects of TAK-981 and cytarabine. Viable cells were estimated by flow cytometric analysis of primary AML cells treated with TAK-981, cytarabine, or both. Error bars are standard errors. (B) Synergistic combination index between TAK-981 and cytarabine from data in panel A. (C) Leukemic cell gating (left) and representative data of flow cytometry for apoptosis of primary AML cells at different concentrations of TAK-981 with DAPI and Annexin V.