Momelotinib inhibits MYC expression and reduces viability and colony formation of primary AML samples. (A) Bone marrow mononuclear cells harvested from 8 untreated patients with AML were treated with momelotinib (CYT) at the indicated concentrations for 72 hours, at which point relative viable cell number was determined by adenosine triphosphate–dependent bioluminescence. (B) Primary AML samples were treated with vehicle, momelotinib (CYT; 2.5 µM), or ruxolitinib (2.5 µM) for 6 hours, after which RNA was harvested for c-MYC quantitation by RT-PCR. (C) CFU-GEMM assays were performed on 4 primary AML samples and CD34⁺ bone marrow cells from 3 healthy donors, each performed in triplicate. Momelotinib treatment caused a dose-dependent decrease in colony formation in both AML samples and CD34⁺ controls, with a more pronounced effect on AML samples. Data are normalized to the DMSO-treated control, and the number of input cells. Statistically significant differences between AML and control samples treated with the same concentration of momelotinib are indicated. ***P < .001, **P < .01.