JNJ-75276617 inhibits proliferation and induces differentiation and apoptosis of KMT2A-altered and NPM1-mutant primary AML or B-ALL patient samples. (A) The effect of JNJ-75276617 on viability of primary AML patient samples was tested in cocultures of mononuclear cells from primary AMLs, enriched by CD34⁺ or CD117⁺ selection, and MS5 murine stromal cells. Cell number was counted after 5 different human AML patient samples (with the noted mutations) were treated with JNJ-75276617 at the indicated concentrations for 7 days. CD11b staining was performed to assess differentiation in response to treatment. Test conditions were run in triplicate. Average values of DMSO control are indicated by horizontal dashed lines. Significant difference compared with DMSO control is indicated (∗P < .001, ∗∗P < .01, ∗∗∗P < .05). (B) The effect of JNJ-75276617 on viability of primary KMT2A-r B-ALL patient sample was tested in liquid culture. Cell number was counted after treatment of JNJ-75276617 at the indicated concentrations for 8 days. Test conditions were run in triplicate. Average values of DMSO control are indicated by horizontal dashed lines. Significant difference compared with DMSO control is indicated (∗P < .001). (C) Flow cytometry analysis of apoptosis in primary KMT2A-r B-ALL patient sample following treatment with various concentrations of JNJ-75276617 for 8 days. On day 8, cells were stained with CD45-PECy7 and annexin V APC, in a 96-well plate, and were incubated for 30 minutes at 4°C. Apoptosis was evaluated in the total cell population. Triplicate samples were tested for each condition, and bars represent the mean ± standard deviation. The experiment was performed once.