the Relationship Between Social Deprivation and Immune Suppression in Hispanic/Latina Patients with Breast Cancer

Immunosuppressive cells, such as myeloid-derived suppressor cells (MDSCs), prevent tumor infiltrating-lymphocytes (TILs) from mounting an anti-tumoral immune response in solid tumors, including breast cancer. Even though genetic factors, such as race and ethnicity, are suspected to contribute to immunosuppression, social determinants of health—non-medical factors including economic stability, education access and quality, health care access and quality, neighborhood and built environment, and social and community context—may also contribute to observed differences in tumor growth and therapeutic response across different racial and ethnic groups. We hypothesized that the combined effects of Hispanic/Latina origin and higher social deprivation contribute to an increased proportion of immunosuppressive cells in circulation. In this study, our IRB-approved cohort consisted of 131 patients with varied histologic subtypes and stages of breast cancer including 71 Hispanic/Latina (H/L), 37 Non-Hispanic White (NHW), 15 Asian, and 8 African American/Black (AAB) individuals. To assess the proportion of immunosuppressive cells in circulation, we performed flow cytometry analysis of peripheral blood mononuclear cell (PBMC) samples obtained from our cohort. To study social determinants of health across racial and ethnic groups, we utilized the Social Deprivation Index (SDI) as a proxy using each patient’s ZIP Code and stratified SDI values into quartiles (where lower quartile indicates less social deprivation). Preliminary data suggested that H/L groups have a greater percentage of circulating suppressive granulocytic (G)-MDSCs (0.31% vs. 0.14%) compared to NHW groups. A similar trend was noted for regulatory T cells with 1.51% in H/L and 1.22% in NHW. This finding also appeared to continue when further adding social deprivation, where groups with both higher social deprivation and H/L origin demonstrated a trending increase in G-MDSCs and monocytic (M)-MDSCs. Preliminary differences in circulating immune cells in in the H/L group could be driven by genetic differences in one or more of the ancestral components and/or by specific exposures that may be more prevalent among H/L women, such as stress, environmental exposures, or others. We are investigating additional data from patient surveys to further inform the observed correlations between SDOH and immune cell differences. Studies are also underway to examine differences in intratumoral immune suppressive cell types in a subset of 13 tumor specimens from 3 H/L and 9 NHW patients with early-stage hormone receptor positive breast cancer. These findings demonstrate the importance of further investigation of the multi-level determinants of response to treatment, especially in patients receiving immune checkpoint inhibitors across diverse racial and socioeconomic populations. Elexa P. Rallos, Sabrina Carrel, Michelle Li, Batul Al-Zubeidy, Edgar Gonzalez, Aaron G. Baugh, Matthew Jacobo, Cheol Park, Robert Hsu, Dominic Zavala, Steven Do, Michael F. Press, Ming Li, Anastasia Martynova, Priya Jayachandran, Daphne Stewart, Chanita Hughes-Halbert, Mariana C. Stern, Evanthia T. Roussos Torres. The relationship between social deprivation and immune suppression in Hispanic/Latina patients with breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7100.