Abstract 1206: Three-dimensional immune atlas of pancreatic cancer precursor lesions reveals large inter- and intra-lesion heterogeneity

Abstract Immunotherapies are generally ineffective in pancreatic ductal adenocarcinoma (PDAC). Paradoxically, inflammation is believed to play a key role in PDAC development and invasion: patients suffering from chronic pancreatitis have a 13-fold increase in risk of developing PDAC. PDAC cells are surrounded by a dense network of fibrotic tissue containing immunosuppressive cells such as regulatory T cells, tumor-associated macrophages, and cancer-associated fibroblasts. Better understanding of the role of inflammation in PDAC could lead to the design of effective immunotherapies. Pancreatic intraepithelial neoplasia (PanIN) is a precursor to PDAC. While most of us will develop PanINs, few of these lesions will progress to invasive cancer. Efforts to determine which PanINs are likely to progress have shown that the size, incidence, and genetic variation of these lesions is high. Here, we add to these efforts through in-depth quantitative analysis of the pancreatic immune microenvironment. CODA is a novel 3D imaging technique used extensively to study the structure, transcriptomic signatures, and genetic heterogeneity of PanINs. In serial histological samples, CODA integrates image registration, cell detection, and segmentation of nine pancreatic structures: PanIN, normal ducts, islets, acini, nerves, vasculature, fat, stroma, and immune aggregates. Through integration with CD45, CD3, and FoxP3 labelled images, we explored immune infiltration in 48 large (cm3) samples of human pancreas tissues containing 1, 000 PanIN lesions to describe spatial correlations between local immune hotspots, 3D tumor morphology, and the surrounding pancreas structures. We quantified inter- and intra-sample heterogeneity in immune response to pancreatic cancer precursor lesions. We determined that this cohort varied greatly in both the number of PanIN (range 3 - 92 per cm3) and overall immune cell density (range 3, 000 - 40, 000 immune cells/mm3). We determined that, while PanIN size is not related to local immune cell density, overall PanIN burden is highly correlated to global immune cell density. This suggests that PanIN content does not have a short-range relationship to inflammation, but does have a long-range relationship with pancreatic structures and immune infiltration. As chronic inflammation in the pancreas shows correlation with development of pancreatic cancer, increased knowledge of the heterogeneous, local immune cell environment in precancerous samples will help us determine the role of inflammation in reacting to and controlling malignant progression. Citation Format: Ashley L. Kiemen, Cristina Almagro-Pérez, Valentina Matos-Romero, Alicia M. Braxton, Jaanvi Mahesh-Babu, Elizabeth D. Thompson, Toby C. Cornish, PeiHsun Wu, Laura D. Wood, Arrate Muñoz-Barrutia, Ralph H. Hruban, Denis Wirtz. Three-dimensional immune atlas of pancreatic cancer precursor lesions reveals large inter- and intra-lesion heterogeneity 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 1206.