Abstract 3805: Immunologic transcript and cell type evaluation of prostate tumors from a military cohort of African American and Caucasian American patients
Authors: Schafer Cara C. , Jiang Jiji , Elsamanoudi Sally , Nousome Darryl , Young Denise , Song Yingjie , Sesterhenn Isabell , Chesnut Gregory , Tan Shyh-Han 
Published: June 2022

Background: Health and racial disparities in prostate cancer place African American (AA) men at greater risk of developing and having a poorer outcome from the disease, especially at a younger age compared to Caucasian American (CA) men. This incidence is also reflected among active-duty service members, and patient biospecimens obtained from an equal access healthcare setting at the Walter Reed National Military Medical Center provide a valuable resource for the evaluation of cancer health disparities. The objectives of this study are to identify immunobiological differences influencing prostate cancer disparities and to elucidate the immune cell profiles of patient tumors associated with advanced disease.

Methods: Patients provided written consent to both biospecimen and clinical database collection under IRB-approved protocols. Fresh frozen tumor biopsy tissues were collected ex vivo, following radical prostatectomy. Total tumor RNA was amplified by PCR-based multiplexed target enrichment, and barcode-tagged transcripts were quantified using NanoString technology. Raw and relative abundances of immune cells were determined using published deconvolution algorithms. Differential expression of immune-related genes and cell type contrasts were evaluated for correlation with clinico-pathologic features.

Results: Genes regulating metabolism and innate immune responses were differentially expressed between AA and CA prostate tumors (AA n=26, CA n=25). Comparing high vs. low expression of each of these top genes, two were associated with biochemical recurrence (BCR)-free survival. Most immune cell subtypes did not differ significantly between AA and CA, but mast cells appeared to be enriched within AA tumors. When cell types were stratified by clinical and pathologic variables, we identified consistent trends in immune cell content that changed with increasing diagnostic age, PSA group, Grade Group, Gleason Sum, and with disease progression as defined by future development of BCR and/or metastasis.

Conclusions: Attention should be directed toward observed immunobiological differences based on race and other clinico-pathologic factors at the time of radical prostatectomy. Patient-centered studies mindful of existing health disparities will aid in diagnostic and therapeutic strategies that are inclusive of an increasingly diverse US and US military population.

Disclaimer: The contents of this publication are the sole responsibility of the authors and do not necessarily reflect the views, opinions or policies of the USUHS, HJF, the DoD or the Departments of the Army, Navy, or Air Force. Mention of trade names, commercial products, or organizations does not imply endorsement by the U.S. Government.

IRB protocol: DBS.2019.032 (Ref Number 930187)

Citation Format: Cara C. Schafer, Jiji Jiang, Sally Elsamanoudi, Darryl Nousome, Denise Young, Yingjie Song, Isabell Sesterhenn, Gregory Chesnut, Shyh-Han Tan. Immunologic transcript and cell type evaluation of prostate tumors from a military cohort of African American and Caucasian American patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3805.