Abstract 1534: The tumor immune microenvironment at different stages of non-small cell lung cancer

Abstract Introduction: To better understand the immune microenvironment in non-small cell lung cancer (NSCLC), we evaluated immune cell populations within the tumor parenchyma and their interaction at the periphery of the tumors at different stages of disease. Methods: 27 whole tumor slides were collected from NSCLC patients of all stages after surgical resection. Tissue slides were stained with multiplex Opal immunofluorescence for CD8, CD68, CK, PD-1, PD-L1, FoxP3, and DAPI using a Leica Bond automated stainer. Slides were scanned at 20x magnification by Akoya Polaris whole slide scanner and spectrally unmixed. Spatial analyses were performed on the HALO software. Results: Density of CD8 T cells, T regulatory (Treg) cells, and macrophages were significantly higher (p=0. 001) in the interface region compared to the tumor and stroma. There is abundant CD8 T cell infiltration in the tumor at early stage I and this decreased significantly (p=0. 05) at higher stages. PD-1− CD8 T cells significantly dropped with higher stage, while PD-1+ CD8 T cells did not. On the other hand, macrophage infiltration increased as stage increased, with most of the increase driven by PD-L1− macrophages. No statistically significant trends were observed in Treg cells across stages, but they appeared to be higher in stage II. No differences in immune infiltration were observed between the NSCLC subtypes adenocarcinoma and squamous cell carcinoma. No correlation was found between proximity of immune cell subsets to tumor cells and stage. Conclusion: The tumor microenvironment in NSCLC is rich in CD8+ cells at early stage and their density decreases as the stage of the disease increases, while macrophage infiltration increases as the disease stage progresses. Citation Format: Mackenzie Hansen, Qin Zhou, Yoko S. DeRose, Magdalena Kovacsovics, Benjamin Brintz, Benjamin L. Witt, Kim L. O'Neill, Siwen Hu-Lieskovan. The tumor immune microenvironment at different stages of non-small cell lung cancer 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 1534.