Abstract 994: Single analyte profiling of the mutational, immune and microbiome landscape in african american colon cancer patients

Abstract Colorectal cancer (CRC) disproportionately affects African American (AA) patients who experience a higher incidence and mortality than any other demographic groups in the United States. Yet molecular profiling in this population is scarce. Here, we performed whole-exome sequencing (WES) of 342 immediately snap-frozen tissues comprising AA CRC and matched, distant normal colon and identified distinct genomic drivers, DNA signatures, and, surprisingly, mosaic pathogenic mutations that are not present in the patient-matched CRC. We inferred T cell infiltration and tissue-resident microbiome (TR-M) directly from WES, enabling integrative analyses. Compared to normal colon, T cell infiltration is strongly decreased in tumours with microsatellite stability (MSS), while microsatellite unstable (MSI) and Polymerase Epsilon (POLE) mutant tumours had similar levels, suggesting immune evasion in MSS rather than increased T cell infiltration in MSI/POLE-mutants. Analyses of matched normal and tumour tissues revealed the evolving TR-M at unprecedented granularity and identified distinct niches of interactions with genomic and tumour-microenvironmental features. Together, this study represents the largest comprehensive genomic analysis of CRC in AA and provides a framework for performing a multi-layered analysis from a single analyte, thus, affording a cost-effective approach to expedite medical discoveries in underrepresented ancestries. Citation Format: Carino Gurjao, Edmond Chan, Michael J. Lee, Sho Hangai, Raul Rabadan, Tal Korem, Hanina Hibshoosh, Benjamin Izar. Single analyte profiling of the mutational, immune and microbiome landscape in african american colon cancer patients abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 994.