MP-A08 and venetoclax induces potent synergistic activity in AML cell lines. (A) MV411 cells were treated for up to 6 hours with 20 μM MP-A08 (blue bars), 10 nM venetoclax (red bars), alone or in combination (green bars). Cell viability was analyzed every 2 hours by Annexin V/propidium iodide staining. Data are means ± standard error of the mean (SEM; n = 4). Statistical significance was assessed by Student t test. ****P < .0001. Drug synergy was assessed with the Chou-Talay combination index (CI) method whereby CI values <1 are classified as synergy. (B) Factor-dependent myeloid wild-type and Bax/Bak^−/− cells treated with MP-A08 (20 μM) and/or venetoclax (10 nM). Data are the mean ± SEM (n = 4). Statistical significance was assessed by Student t test. ****P < .0001. MV411 (C-D), HL-60 (E), MOLM13 (F), and OCI-AML3 (G). (H) MV411 cells were stably transduced with a doxycycline-inducible shRNA targeting Bcl-2 and treated with doxycycline (1 μg/mL) for 48 hours and MP-A08 (10 μM) for 24 hours. Cell viability was assessed by Annexin V staining. All data are the mean ± SEM of 3 independent experiments. Statistical significance was assessed by Student t test. ***P < .0001. (I) UT-7 cells were treated with MP-A08 and venetoclax for 24 hours and assessed for cell viability by Annexin V/propidium iodide staining. Drug synergy was assessed using the Chou-Talay CI method. (J) UT-7 cells were treated with increasing concentrations of MP-A08 for 6 hours and subjected to immunoblot analysis. MV411 (K) and OCI-AML3 (L) cells were treated with MP-A08, venetoclax, or in combination for 6 hours and subjected to immunoblot analysis with the indicated antibodies. All qualitative data are representative of at least 3 independent experiments, and all quantitative data are the mean ± SEM of at least 3 independent experiments.