Abstract 2362: Spatial transcriptomic landscape of primary and lymph node metastatic pancreatic cancer
Authors: Hong Changjin , Clemenceau Jean R. , Graham Rondell P. , Hwang Tae Hyun 
Published: April 2023

Abstract
Background: Spatial molecular analysis can provide functional characteristics of cellular components and their interactions present in the tumor immune microenvironment (TME), thus improving our understanding of the cancer ecosystem at a systemic level. We investigated the spatial and functional characteristics of the tumor, stroma, and immune cells, and their roles in the TME in facilitating cancer development, progression, and metastasis in pancreatic cancer.
Methods: We performed spatial profiles of multiple regional TMEs of 13 pancreatic cancers (7 pancreatic adenocarcinoma, 3 pancreatic neuroendocrine, and 3 acinar cell carcinomas) using NanoString GeoMX at the whole transcriptome level (18,676 genes). We collected a total of 23 tissue samples containing matched primary tumors, adjacent normal pancreatic tissue, or normal/metastatic lymph node. Tumor, stroma, and immune cells are stained by PanCK, αSMA, and CD45 markers, respectively. We selected 234 regions of interest (ROIs) in the tumor core, border, adjacent normal pancreas, and lymph node to investigate spatial patterns of different cells and their cellular interactions in neighborhoods from paired primary and metastatic tumors.
Results: TMEs in different ROIs are spatially correlated within a tumor but showed distinct phenotypes across tumors and tumor types. Each cell type in the ROIs has a unique role to drive cancer evolution in TMEs. Diverse types of cancer-associated fibroblasts (CAFs) are present in primary and metastatic TME, while CAFs in tumor border and metastatic lymph nodes showed mainly enriched with antigen-presenting CAF (apCAF) subtypes with higher extracellular matrix (ECM) and collagen fibrils components. Similarly, we found diverse functional phenotypes of the immune cell in TMEs. The immune response signaling pathway is activated in the stroma-infiltrated immune cells, but, in fact, not in the tumor-infiltrated immune cells. Instead, higher dysfunctional T cell and growth factors are present in the stroma-infiltrated immune cells from primary and metastatic tumors, but not in stromal immune normal pancreatic and lymph node tissues. The tumor-infiltrated immune cells showed suppressive immune activities by increasing TGFβ receptor signaling. We also discovered CCL5-driven metastatic patterns in TMEs from primary tumors and metastatic lymph nodes. Lastly, we concluded that these functional phenotypes of cells in TMEs are preserved in a certain pancreatic cancer type, suggesting the origin and evolution of different pancreatic tumors could be driven by diverse cellular and functional phenotypes of cells in TMEs.
Conclusion: Our comprehensive analysis results demonstrate that the spatial analysis could provide insights into the spatial patterns that drive cancer evolution in pancreatic TMEs, thus helping understand the cellular microenvironment governing pancreatic cancer metastasis.
Citation Format: Changjin Hong, Jean R. Clemenceau, Rondell P. Graham, Tae Hyun Hwang. Spatial transcriptomic landscape of primary and lymph node metastatic pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2362.