In contrast to modest single agent activity observed from targeting BCL-2, BCL-XL, or MCL1 alone, marked anti-leukemic activity (LC50 sensitivity < 100 nM) was apparent in > 50% of the primary AML samples when treated simultaneously with equimolar concentrations of BH3-mimetics targeting BCL-2 and MCL1 (Fig. 1a, b). Here, MCL1 is linked to acute myeloid leukemia.