Abstract B018: Quantification of immune cell subtypes identified in the pancreatic tumor microenvironment using multiple immunostaining techniques and analysis of correlation between immune cells and patient survival rates
Authors: Jeong Ji Hye , Ko Eun-Young , Kim Sang-Yeob , Jun Eunsung 
Published: January 2024

Abstract
Pancreatic cancer (PC), known as one of the solid cancers with an extremely poor prognosis, exhibits limited responsiveness not only to conventional chemotherapy but also to recent immunotherapy approaches. To develop an effective immunotherapeutic agent for pancreatic cancer, it is necessary to identify the underlying factors that limit the effect of immune checkpoint inhibitors and conduct more comprehensive studies on the tumor microenvironment and tumor immune environment. In this study, we aimed to find a clue to the development of a new treatment by identifying the immune environment of PC through the analysis of immune cell subtypes in the patient's tumor tissue and the correlation analysis with clinical factors such as the patient's prognosis. For quantitative analysis of immune cell subtypes in tissues, multiplex Immunohistochemistry was performed using markers for T cells, B cell, macrophages, dendritic cells and NK cells. Then, the stained slides were analyzed by using inForm software. To analyze the association with the extracellular matrix (ECM) in the tissue, the amount and intensity of ECM were analyzed through Masson's trichrome staining. These data obtained from patient tissues were investigated for correlation with various clinical factors. First, comparison groups were formed according to the quantitative values of immune cell subtype, and then, through analysis of the relationship with the survival rate of patients in each group, it was confirmed that the survival rate of the T cell high (Tc-hi) group was significantly better than that of the T cell low (Tc-lo) group. In addition, there was a negative correlation between CA19-9 level and the patient's prognosis, which was statistically significant in the Tc-lo group, but not the Tc-hi group. Second, it was confirmed that the number of tumor cells distributed in the radius of 15~30μm of dendritic cells and NK cells decreased in Tc-lo group. Finally, the distribution of immune cells, according to the amount and intensity of ECM in tumor tissue was compared. Interestingly, the amount of ECM was rather higher in the Tc-hi group than in the Tc-lo group. In addition, the immune cell infiltration decreased as the amount of ECM increased in the Tc-hi group, whereas the Tc-low group showed the opposite result. This difference is more distinct in the subgroup analysis according to ECM strength. In the Tc-hi, there was a positive correlation between ECM and T cells in areas with sparse ECM, but a negative correlation was seen in areas with dense ECM. Through this study, we performed a quantitative analysis of various immune cell subtypes present in the immune microenvironment of the PC, and confirmed the correlation with the survival rate accordingly. In addition, it was confirmed that the penetration of immune cells can be different depending on the total amount and strength of ECM present in these distributions. Therefore, we hope that these results might be provided clues to the development of PC-specific immunotherapeutic agents.
Citation Format: Ji Hye Jeong, Eun-Young Ko, Sang-Yeob Kim, Eunsung Jun. Quantification of immune cell subtypes identified in the pancreatic tumor microenvironment using multiple immunostaining techniques and analysis of correlation between immune cells and patient survival rates [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B018.