Abstract PR18: The immune landscape of prostate cancer in African-American patients is skewed towards inhibitory signatures relative to Caucasian-American patients

Abstract

Abstract Prostate Cancer is a leading cause of cancer-related deaths among men in the United States. Within the general population, African-Americans who constitute a minority group suffer a higher burden of the disease compared to other racial groups. Given that immune cells recruited to the tumor micro-environment shape tumor behavior, an outstanding issue is whether the immunological landscape of prostate cancer in African-American patients is a contributory factor to disease disparity seen in this minority patient population. In this regard, the present study sought to investigate whether prostate cancer in African-American men harbor distinctive immunological features compared to their Caucasian counterparts. Fresh prostate cancer specimens were obtained from consented African-American and Caucasian patients after prostatectomy. Gleason scores were comparable between the two demographics with an average score of 7 for African-American patients and 7.5 for Caucasian patients. We analyzed both tumor and matched peripheral blood mononuclear cells from each patient using comprehensive, multi-parameter flow cytometry. We found that both CD4+ and CD8+ T cells in African-American prostate cancer displayed upregulated expression of a number of inhibitory proteins that restrain T cell response. These cells also expressed reduced levels of co-stimulatory receptors and a less activated phenotype compared to equivalent cells in the tumors of Caucasian patients. Furthermore, analysis of serum from patients in each demographic revealed an enrichment of cytokines skewed towards immunosuppressive profile which may support reduced immune cell function against tumor-associated antigens. These findings suggest that the immunological profile of prostate cancer in African-American men harbors intrinsic signatures that may contribute to muting of potential anti-tumor responses in this patient demographic, enabling tumor immune evasion to support aggressive tumor growth and progression. Collectively, our data is in support of the contributory role of immunological factors to disease behavior and associated disparity in African-American prostate cancer patients. Citation Format: Andrew Schultz, David Noyes, Arup Bag, Dennis Adeegbe. The immune landscape of prostate cancer in African-American patients is skewed towards inhibitory signatures relative to Caucasian-American patients [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PR18.