All combinations were synergistic and shifted the equilibrium towards cell death, but especially combined treatment with S63845 and ABT737 or A-1155463 showed strong synergism in both patient samples, indicating that concomitant inhibition of both MCL-1 and BCL-XL is synergistically lethal in JMML (Fig. 6D, E). Here, MCL1 is linked to juvenile myelomonocytic leukemia.