Abstract C165: Interrogating the Tumor and Immune Microenvironment of Endometrial Cancers Among a Diverse Cohort of Cases

Abstract Endometrial cancer (EC) is the sixth most common gynecological malignancy, with an increasing incidence worldwide over the last two decades. African American women are more likely to be diagnosed with endometrial cancer than Caucasian women. Unfortunately, African American women are more frequently diagnosed with high-grade EC, which occurs 2-3 times more often compared to their white and Hispanic counterparts. Additionally, African American women have higher mortality rates from EC than Caucasian women, highlighting a significant cancer disparity among these patients. Uterine EC disparities are induced by complex ecosystems composed of cellular niches with distinct genotypes, phenotypes, and spatial transcriptomic landscapes. In estrogen-dependent EC tumorigenesis, the endometrium undergoes uncontrollable proliferation, progressing from normal to atypical hyperplasia and ultimately to carcinoma. The heterogeneity of EC tumors complicates therapeutic targeting, rendering EC a challenging disease to cure. This study aims to investigate the genetic and transcriptomic features found in the tumor microenvironment of African American patients with EC. Previous research has shown that the molecular classification of EC tumors can be categorized as estrogen-driven, hypermutant, microsatellite instable, or lacking a specific molecular profile. Current models do not adequately reflect the oncogenic origin and pathological progression in patients. The cohort of EC cases includes primary, metastatic, and normal tumor tissues classified as Uterine Endometrial Adenocarcinoma, along with two Serous Papillary cases with varying tumor grades (low to high grade). Spatial transcriptomics and whole exome sequencing were performed on these samples. Spatial transcriptomics will identify the alterations in gene expression and the spatial landscape of the cell neighborhoods driving tumor heterogeneity. Whole exome sequencing will provide insight into the germline and somatic variants present in EC, offering a deeper understanding of the potential genetic drivers in African American patients. The genes expressed across the EC tumor landscape are implicated in cell proliferation, epithelial- mesenchymal transition, DNA damage response, and immune response. The analysis will also show the transition of normal to malignant endometrium harboring high tumor mutational burden and microsatellite instability when comparing paired samples. This comprehensive approach aims to elucidate the genetic and transcriptomic underpinnings contributing to the disparities observed in African American patients with EC, ultimately informing better-targeted therapies and improving outcomes. Citation Format: Danyelle Paine, John Carpten. Interrogating the Tumor and Immune Microenvironment of Endometrial Cancers Among a Diverse Cohort of Cases abstract. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C165.