Abstract C013: Uncovering bacterial taxa associated with ocular surface squamous neoplasia (OSSN) through 16s rRNA gene sequencing

Abstract Ocular Surface Squamous Neoplasia (OSSN) encompasses a range of disease states from mild dysplasia to carcinoma of the squamous epithelium. This disease occurs in regions with high UV-B exposure, immunocompromised populations, and oncogenic viral epidemics. Historically, OSSN occurrs in Caucasian men in the 6th or 7th decade of life however, recently, OSSN incidence has increased in younger and non-Caucasian populations. Sub-Saharan Africa has an OSSN incidence rate over 2-fold greater than the United States. For example, in Zambia, ocular cancers as a whole are the 5th most common cancer. Initial work in the field investigated oncogenic viruses as potential causative agents for OSSN, however the precise etiology of OSSN remains unclear. Our previous findings indicated that Epstein-Barr Virus (EBV) and not Human Papilloma Viruses are associated with OSSN. Thus, we hypothesized that OSSN is induced by oncogenic viruses and inflammation. Given that bacterial infections can activate inflammation, cause DNA damage, and in immunocompromised patients may persist as chronic infections we posit that bacteria may play a role in initiating and/or driving OSSN development. To better understand the etiology of OSSN, we investigated the in-tumor bacteriome of 53 OSSN tumor samples through NGS of variable region 4 of the 16s rRNA gene. We predict that bacterial taxa diversity and abundance will differ as a result of HIV Status and Tumor Grade. Identifying bacteria which were within the tumor environment, preliminary analysis indicates that there is no difference between bacterial alpha-diversity (Chao1, Simpson, Shannon, and Observed) or beta-diversity (UniFrac) for patients with or without HIV. Given that HIV patients have reportedly decreased bacterial diversity compared to non-HIV patients, this may indicate a bacterial community structure which is associated with OSSN. Additionally, preliminary analysis indicates that there is no difference between bacterial alpha-diversity for patients with or without EBV. Additional samples are currently being sequenced to improve sample size for the various Tumor Grades. Further analysis is currently ongoing. In conjunction, we have utilized multiplex PCR to qualitatively survey for bacterial species in OSSN tumors. No species surveyed differed significantly as a function of HIV status. We find that Corynebacterium tuberculostearicum is present more often in EBV negative samples (N= 174; Fisher’s Exact = 0.0009). We find that Lactobacillus jensenii and Staphylococcus aureus are both found more often in Invasive tumors compared to pre-invasive tumors (N= 228) (Fisher’s Exact = 0.001 and 0.006 respectively). These preliminary findings indicate that OSSN may have a genus level community structure which is not differentiated by significant epidemiological factors such as HIV status. However, species specific analysis indicates species level changes which may be informative for OSSN etiology. Together, these may offer the framework for rapid, non-invasive means for identifying or grading OSSN severity. Citation Format: Ken Kugel, Peter Julius, Stepfanie N. Siyumbwa, Fred Maate, Phyllis Moonga, Guobin Kang, Trevor Kaile, John T. West, Charles Wood, Samodha Fernando, Peter C. Angeletti. Uncovering bacterial taxa associated with ocular surface squamous neoplasia (OSSN) through 16s rRNA gene sequencing [abstract]. In: Proceedings of the 18th AACR Conference on the Science of Cancer Health Disparities; 2025 Sep 18-21; Baltimore, MD. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2025;34(9 Suppl):Abstract nr C013.