AML cell populations display distinct gene expression and drug sensitivity profiles at the single-cell level. (A) Uniform Manifold Approximation and Projection (UMAP) representation of the cell types identified from single-cell RNA sequencing data from samples from 7 patients with AML. The group consisted of 1 patient with monosomy 7 and 6 patients with AML without -7/-7q. Cells are colored based on clusters identified using ScType and in-house gene sets. (B) UMAP representation of log normalized NAMPT gene expression level across the total cell cohort. NAMPT expression increases toward the differentiated myeloid cell types. (C) UMAP representation of log normalized BCL2 gene expression. Cells that belong to the HSC/progenitor-like cell cluster show the most expression in the myeloid cells. (D) Violin plot showing log normalized NAMPT gene expression in CD34⁺CD38^– and CD34⁺CD38⁺ cells. Cells were selected from the total cell cohort based on their CD34 and CD38 expression levels. NAMPT expression is significantly lower in cells from the patient with monosomy 7 than cells from the patients without -7/-7q. In the samples without -7/-7q, NAMPT expression is significantly higher in CD34⁺CD38⁺ cells than in CD34⁺CD38^– cells. Comparisons were done using the Mann-Whitney U test. (E) Violin plot showing scaled NAMPT gene expression in the 11 different cell clusters. NAMPT expression is highest in the more-differentiated myeloid cells (erythroid-like, neutrophil-like, and monocyte-like cells) compared with myeloid progenitor or lymphoid cells. Scaled expression values were calculated using Seurat functions to bring NAMPT and BCL2 expression to the same level for a more accurate comparison. (F) Violin plot showing scaled NAMPT expression in different myeloid and lymphoid cells in healthy BM cells. Expression data are obtained from 8 different donors from the Human Cell Atlas. (G) Violin plot showing scaled BCL2 gene expression in cell clusters. BCL2 is expressed at a significantly higher level in the HSC/progenitor-like cells than other myeloid cell clusters. Mean gene expression is marked with thick lines in each violin plot. Cell clusters in each violin plot were compared with each other with Dunn test followed by the Kruskal-Wallis H test. (H) Dotplot illustrating the proportion of total blast killing as measured by multiparametric flow cytometry in 3 distinct samples from patients with AML with -7/-7q after incubation for 72 hours with NAMPT inhibitor KPT-9274 at 100 nM (light gray), BCL2 inhibitor venetoclax at 30 nM (dark gray), or a combination of both agents (orange). The combination leads to the death of significantly more AML blasts than the NAMPT inhibitor alone due to an additive effect. Statistical comparisons by the Tukey test subsequent to an ANOVA. ∗ P < .05; ∗∗ P < .01; ∗∗∗ P < .001; ∗∗∗∗ P < .0001. ANOVA, analysis of variance; mDC, myeloid dendritic cells; NK cells, natural killer cells; pDC, plasmacytoid dendritic cells.