Abstract B055: Characterization of immune cell subsets from tissue expression profiles in African American triple-negative breast cancer patients

Abstract

Abstract Triple-negative breast cancer (TNBC) is more frequent and aggressive in African American women and women of African descent. The heterogeneity of TNBC has become a challenge in today's clinical practice, and significant research efforts have been deployed to better understand the molecular nature of TNBC. Clinically, the heterogeneous nature of TNBC has not been accounted for, hence leading to therapy resistance, metastasis, and relapse. TNBC has been associated with an elevation of immune infiltrates, which suggests that some patients may benefit from immune-based therapies. In this study, we used analytical tools that perform cell type enrichment analysis and provide an estimation of the abundances of immune cell types in a mixed cell population using gene expression data to compare the differences among immune cell types between African and Caucasian American breast cancer patient samples. Here, we examined RNA-sequencing data from 1,215 patients from two breast cancer cohorts including The Cancer Genome Atlas, which consists of 32 African American and 64 Caucasian TNBC samples, and data from 130 breast cancer cases with extensive clinical annotation collected and accrued from rural regions of eastern North Carolina in collaboration with Noreen Vohra at the Brody School of Medicine at East Carolina University. This cohort contained data from 23 African American TNBC samples and 25 Caucasian TNBC samples. Results revealed that tumor-associated macrophages and T cells were significantly represented among TNBC patients in both datasets with uncommitted macrophages (M0), M2-like macrophages, and CD4 memory resting cells as the predominant populations. Additionally, known antitumor immune cells, such as CD8 T cells and NK cells, were under-represented among TNBC patients. Although expression of immune cells and immune cell subsets was represented in our datasets, we did not find any significant difference between African American and Caucasian TNBC patients. We plan to present analyses from this data stratifying cases by mutational burden and expression of immune checkpoint markers. Our findings suggest that TNBC patients could possibly benefit from immunotherapies and their therapy could be personalized to their immune profile. Therefore, immune profiling may unlock new therapeutic opportunities for African American TNBC patients. Citation Format: Lee D. Gibbs, Jung Byun, Tingfen Yan, Anna Napoles, Eliseo Pere-Stables, Troy McEachron, Nasreen Vohra, John D. Carpten, Kevin Gardner. Characterization of immune cell subsets from tissue expression profiles in African American triple-negative breast cancer patients [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr B055.