Abstract A025: Profiling tumor infiltrating immune cells for better understanding tumor status and better response to therapeutic strategy in soft tissue sarcomas

Abstract The tumor microenvironment is closely associated with tumor development and progression, which is made up of tumor cells, blood vessels, immune cells, fibroblast, and so on. Especially, immune cells within tumor microenvironments have been attracted in clinicians and researchers for unexpected therapeutic responses. Even in sarcoma, which is rare, and heterogenous leading to few options for cure, immune therapy has been tried and shown to be promising. However, the information of immune cells within soft tissue sarcomas were limited, which mostly have been obtained and characterized by omics-based analyses or tissue staining such as immunohistochemistry. Here, we established platform to profile tumor infiltrating immune cells by flow cytometry. About thirty sarcoma tissues were obtained, in which tumor infiltrating immune cells were profiled. The profiled data were confirmed by immunohistochemistry for correlation. It was shown that infiltrated leukocytes and CD3+ T cells were remarkably increased, whereas NKT and CD4+ T cells were decreased in tumor tissues compared to adjacent normal tissues. M1 macrophage was also increased in tumor tissues. High CD3+ T cell population was positively correlated with CD8+ T cells and PD1+ CD8+ T cell population. Especially, PD1+CD8+ T cells are usually expressed exhaustion-related conditions and low levels of cytotoxic immune cells. This study provides resources to understand immune cell population of soft tissue sarcoma, and will gain a fundamental matrix to study immunotherapy. These studies might show the possibility to find potential prognostic and immunotherapeutic targets. Citation Format: Eun-Young Lee, Hyun Guy Kang, June Hyuk Kim, Jong Woong Park, Seog Yun Park, Tak Yun, Hye Jin You. Profiling tumor infiltrating immune cells for better understanding tumor status and better response to therapeutic strategy in soft tissue sarcomas [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr A025.