Immunogenomic Diversity of Triple-Negative Breast Cancers in Obese and Non-obese Black and White Women

Racial disparities in incidence and outcomes of triple-negative breast cancer (TNBC) have been attributed to ancestry, socioeconomic factors and/or obesity. We studied 253 TNBCs from 128 Black and 125 White women. Arms were balanced for age, AJCC stage, histological grade and molecular subtypes, and differed significantly in BMI distribution, obesity, and Area Deprivation Index. We examined survival rates, whole-transcriptome RNASeq and genetic ancestry. In our sample, Black race or obesity were not intrinsically predictive of poor outcomes. TNBC molecular portraits varied with stage and biological aggressiveness, irrespective of race. We identified a novel group of TNBCs with a distinctive luminal-like and stem-cell-like transcriptional profile that were equally distributed among Blacks and Whites. Genetic ancestry was highly admixed. Immune deconvolution showed a higher abundance of several immune cell populations in tumors from Blacks, which may have precision therapeutic significance, warranting further investigation of potential drivers of tumor immunity. Retrospective, two-arm observational study. The final sample set included 253 TNBCs - from 128 Black and 125 White women. The two arms were balanced with respect to age, AJCC stage, histological grade and molecular subtype. They differed significantly in BMI distribution, obesity rates and Area Deprivation Index. RNAseq was used to determine gene expression profiles associated with TNBC in African American (AA) and European American (EA), with and without obesity, from Louisiana. Gene profiles were used to determine associations with race/ethnicity, obesity stage, tumor stage, prediction of immune infiltration and survival