Abstract 7466: Exploring tertiary lymphoid structures and immune cell interactions in gastric cancer prognosis

Abstract

Abstract Tertiary lymphoid structures (TLSs) are ectopic lymphoid aggregates found in chronically inflamed, infected, and tumor tissues. Prior research indicates that the presence of TLS and tumor-infiltrating lymphocytes (TILs) correlates with a more favorable prognosis in several cancers. Our study investigates the role of TLSs and TILs in gastric cancer, the 4th leading cause of cancer-related death worldwide. We analyzed tumor samples from 107 late-stage gastric cancer patients from mainland China, with a 5-year follow-up period. We performed H&E and multiplex immunofluorescence staining to assess the tumor area and infiltrating immune cells, and we evaluated potential relationships between TILs, clinicopathological features, and patient prognosis. Immunohistological analysis showed that CD4 T cells may have a more significant impact on patient prognosis than CD8 T cells. Notably, the presence of PDL1 and CD4 co-expressing cells was associated with better disease outcomes. We observed PDL1 expressing cells surrounding the tumor margin in a subset of cases, a distribution pattern that could lead to delayed recurrence or complete remission in gastric cancer. In the context of cancer-related TLS, we found that CD20 and CD86 co-expression in the center of the structures may indicate a higher maturation level. Additionally, the ratio and spatial distribution of CD86 and CD163 macrophages appear to play a crucial role in prognosis. We extracted the expression levels of markers from representative samples to examine the spatial relationships between cancer cells and each immune cell type. We then visualized these cellular interactions in the tumor microenvironment using topographic plots. This study broadens our understanding of tumor and immune cell interactions in gastric cancer, with the potential to inform future directions in immunotherapy treatments. Citation Format: Zheng Zeng, Yee Man Au-Yeung, Jiandong Huang. Exploring tertiary lymphoid structures and immune cell interactions in gastric cancer prognosis [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 7466.