Abstract 1769: Pan-cancer genomic characterization of human papillomavirus associated tumors reveals patterns of somatic alteration that associate with virus status and anatomic site

Abstract Human papilloma virus (HPV) infection causes over 600, 000 human cancers yearly and accounts for nearly all cervical cancers, increasing rates of head and neck squamous cell carcinomas (HNSCC), and many anogenital cancers - all with varying clinical outcomes due to a lack of personalized care. While recent integrative genomic studies have described molecular features of individual cancer types, few studies have compared genomic changes between HPV (+) and HPV (-) cancers across anatomic sites. Here, we conducted the first pan-cancer genomic analysis of HPV-associated tumors across multiple anatomic tumor types using whole exome and transcriptome data from The Cancer Genome Atlas (TCGA) cohorts of cervical (n=254) and HNSCCs (n=514), and targeted exome sequencing of 800 cancer genes plus full length HPV16/18 genomes in a clinical cohort of squamous tumors from the head and neck (n=458), cervix (n=78), vulva (n=23), anal canal (n=5), and vagina (n=2). Somatic variant calling and filtering, followed by an integrative pathway analysis of commonly altered targets, defined the catalog of somatic mutations and copy number alterations (CNAs) that drive HPV (+) and HPV (-) tumorigenesis. Sequencing reads from viral RNA or DNA determined HPV status, and HPV type, genome structure, integration events, and viral load were characterized in a subset of samples via de novo assembly of viral aligned reads followed by copy number analysis, breakpoint identification, and the calling of structural variants. Overall HPV positivity was 50% (668 out of 1334 total), with HPV16 accounting for 96%, 89%, and 60% of all HPV (+) anogenital, head and neck, and cervical tumors respectively. Significant differences in somatic mutation frequency between HPV (+) and HPV (-) tumors were observed in the full cohort, as well as in analyses stratified by anatomic site. Interestingly, we noticed recurrently mutated “hotspots” attributable to increased APOBEC-mutagenesis in HPV (+) samples across anatomic sites (PIK3CA: E545K, FGFR3: S249C, EP300: D1399N), while hotspot mutations likely caused by tobacco smoking predominate HPV (-) HNSCC (PIK3CA: H1047R/L, CDKN2A: R80*, TP53: R282W). Focal and arm level CNAs were distinctive, including gains of 11q22 in HPV (+) cervical and HPV (-) HNSCC, and losses of 11q22 in HPV (+) HNSCC. Biological pathways commonly altered include epithelial differentiation, cell death, innate immunity, growth factor/kinase signaling, and cell cycle control. In summary, pan-cancer genomic analysis revealed distinct patterns of somatic alteration of conserved biological pathways that associate with HPV status and anatomic site. These findings improve our understanding of tumor biology unique to HPV-associated cancers and may lead to novel treatment and classification strategies to improve patient outcomes in the clinical setting. Citation Format: Jeremiah Ray Holt, Paul Little, Heejoon Jo, Xiaobei Zhao, Hyo Young Choi, Vonn Walter, Benjamin Wahle, Jose P. Zevallos, Angela Mazul, Katherine A. Hoadley, Michele Hayward, David N. Hayes. Pan-cancer genomic characterization of human papillomavirus associated tumors reveals patterns of somatic alteration that associate with virus status and anatomic site 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 1769.