Abstract 3647: Digital spatial transcriptomic reveals different epithelial and immune cells signatures across endometriosis-related diseases: From simple ovarian endometriosis to ovarian cancer

Abstract Endometriosis represents a pressing medical concern, imposing a relevant burden on patients including potential malignant transformation into endometriosis-associated ovarian cancer (EAOC). Despite the process of cancer development remains unclear, immune cells abnormalities arose as putative biomarkers in the neoplastic progression. One-third of ovarian endometriosis cases exhibit PD-1/PD-L1 expression levels comparable to those observed in cancer. To substantiate the biological basis of these findings, this study aimed to elucidate the spatial transcriptomic profile of epithelial and immune components from different endometriosis-related conditions, along with their genetic interplay. Formalin-fixed paraffine embedded (FFPE) specimens from 4 ovarian endometriosis (OE) cases, two of which displayed elevated levels of PD-1/PD-L1 expression and were referred to as cancer-like endometriosis (CLE), 1 Clear Cell Ovarian Cancer (CCOC) and 1 Endometrioid Ovarian Cancer (EOC) were cut in 5um section for spatial transcriptomic analysis using GeoMX Human Whole Transcriptome Atlas (WTA) probe-set (>18000 genes). For all sections, the regions of interest (ROIs) were identified using a set of morphology markers: anti-human CD3, CD68 and PanCK antibodies. Spatial transcriptomic analysis revealed condition-specific gene enrichment of epithelial and immune cells across the different conditions. In spite of similar H&E findings, PanCKpos epithelial cells from CLE showed an increased expression of genes involved in stress response and defense regulation pathways (e.g. CXCL6, S100A9, and PECAM-1), when compared to OE, in which PanCKpos cells were enriched in DUSP1/2 and VIM. Interestingly, in CCOC, location-specific gene-enrichment was found in PanCKpos cells, with a significant up regulation of tumor suppressor genes (e.g. EGR-1, NR4A1) in normal-looking peri-tumoral epithelium compared to cancerous intra-tumoral PanCKpos cells. Similarly, in the immune compartment, spatial transcriptomic analysis revealed that CD3pos cells from CLE displayed an up-regulation of genes involved in IL-17 signaling, response to oxydative stress and complement activation (e.g. CXCL6, HMOX1, S100A9, and PECAM-1), when compared to OE. Moreover, in CCOC, CD68pos cells of the tumoral mass showed over-expression of tumor growth and progression markers (e.g. SPP1) compared to their counterpart in the outer area of the tumoral mass. In this first comprehensive spatial transcriptomic study of endometriosis-related diseases with GeoMx WTA, our findings uncovered remarkable differences in epithelial and immune cells among different stages and tissue locations. Importantly, CLE emerged as a transitional entity with a unique immune profile. Ongoing analysis of six additional samples will further refine our results. Citation Format: Valentina Iacobelli, Camilla Nero, Stefano Alivernini, Giulia Scaglione, Floriana Camarda, Francesca Sillano, Rita Trozzi, Alessia Piermattei, Barbara Tolusso, Giulia Mantini, Luciano Giacò, Gloria Anderson, Gian Franco Zannoni, Elisa Gremese, Anna Fagotti, Giovanni Scambia. Digital spatial transcriptomic reveals different epithelial and immune cells signatures across endometriosis-related diseases: From simple ovarian endometriosis to ovarian cancer [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(6_Suppl):Abstract nr 3647.