B7-H3 is overexpressed in AML patients and is associated with poor clinical outcomes. (A) B7-H3 expression in AML patients and control samples. PBMCs from AML patients and healthy donors were stained with CD34-PE and B7-H3-APC (BioLegend, clone MIH42) antibodies and measured B7-H3 expression by flow cytometry (Wilcoxon rank-sum test). (B) B7-H3 expression on CD34⁺ and CD34^- subpopulations in AML patients and controls (Wilcoxon rank-sum test). (C) B7-H3 expression in AML patients stratified based on European LeukemiaNet prognostic risk groups (ie, good, intermediate, and poor risk; Kruskal-Wallis test). (D) Overall survival (OS) of AML patients divided into low and high B7-H3 expression using receiver operating curve (ROC) as a cutoff (log-rank test). (E) Disease-free survival by B7-H3 expression level in patients with AML (RNA expression of B7-H3 obtained from the Oregon Health & Science University [OHSU] AML data set). The cutoff for B7-H3 expression was the median (log-rank test). (F) OS by B7-H3 expression level in patients with AML. (G) B7-H3 and PD-L1 expression in the indicated AML cell lines; leukemic cells (1 × 10⁶) were stained with anti-B7–H3 and anti-PD–L1, and their expression was measured by flow cytometry. Data are plotted as mean values with error bars representing standard error. (H,I) Correlation of B7-H3 (CD276) and PD-L1 (CD274) mRNA expression obtained from the OHSU (H) and The Cancer Genome Atlas (TCGA) (I) AML data sets. The graph was generated using cBioPortal for Cancer Genomics data analysis software. Spearman and Pearson correlation test was used for statistical analysis. ***P < .0001.