Genomic profiling between Hispanic Americans (HA) and non-Hispanic (NHW) with advanced prostate cancer: A retrospective analysis of tissue, liquid, and germline testing

30 Background: Genomic testing through the employment of somatic and germline testing has become increasingly relevant in determining the prognosis and targeted therapies for advanced prostate cancer patients. Prostate cancer health disparities resulting in worse presentations and clinical outcomes have been observed in HA compared to NHW. Understanding the prevalence of different genomic alterations is paramount to bridge the gap between the two ethnic groups. Methods: This is a retrospective analysis of 190 metastatic prostate adenocarcinoma patients with 24.2% HA who presented to the University of Arizona Cancer Center from 2015 to 2022. Patients in both groups may have undergone more than one type of testing. Homologous recombination repair (HRR) included ATM, BRCA1/2, BARD1, BRIP1, CDK12, CHEK1/2, FANCA/L, HDAC2, PALB2, RAD-51B/1C/51D, or 54L. Tissue-agnostic therapy approvals are dMMR, MSI-H, TMB-High, BRAF V600E, and NTRK/RET fusion. The proportion of HA and NHW was determined, and the statistical significance of the differences was reported using Chi2 or Fisher’s Exact test. Results: 43.6%, 34.7%, and 38.9% of patients had somatic tissue, liquid, and germline testing, respectively analyzed for pathogenic variants. TMB-High >10 (30% vs 3.6%, p=0.02), PD-L1 CPS>5 (9.4% vs 0%, p=0.03) and TMPRSS2-ERG fusion (37.5 vs 7.8%, p=0.0009) had higher proportion in HA compared to NHW. No test showed a difference in BRCA 1/2 or another HRR deficiency actionable mutation between the two ethnicities. There were no other statistically significant differences in common mutations or variants of unknown significance among groups. Conclusions: Liquid and tissue biopsies indicated a difference in proportions for tissue-agnostic and immune-oncology therapeutic indications, being more prevalent in HA. TMPRSS2-ERG fusions have differences in PC development and progression by race and now potentially by ethnicity, as shown by our study. Our review revealed increased germline and somatic testing over time according to targeted therapies approval and guideline recommendations, although, there remains a critical need for advancing genomic sequencing efforts for underrepresented HA. The Hispanic Americans Prostate Cancer Comprehensive Genomic Profiling Study's (THAPCA-GPS) future investigations aim to delineate the pathogenetic differences between HA and NHW and may reduce healthcare disparities and improve clinical outcomes in HA patients. [Table: see text]