Abstract 1516: Large scale, transcriptome-based analysis of TCR clonality reveals functional immunity in non-small cell lung cancer

Abstract Tumor-related T-cell activation and subsequent clonal expansion are essential for an effective anti-cancer immune response. Thus, quantifying the clonal distribution of T-cells in cancer tissue from patients might provide prognostic and predictive information, particularly in high immunogenic tumors like non-small cell lung cancer (NSCLC). We evaluated TCR clonality in the tumor microenvironment of NSCLC, its relation to the in situ immune phenotype, and its clinical impact in a cohort of 182 resected NSCLC patients. The α and β TCR clones were determined based on RNA sequencing data, and the Gini index was used to weight individual clonal distribution. We used matched FFPE cancer tissue for multiplex immunofluorescence cell analysis and in-situ sequencing of T-cell clones. The analysis revealed a broad spectrum of TCR clonality patterns, including tissue with high TCR diversity and high evenness (low Gini coefficient) and tissue with clonal dominance with low evenness (high Gini coefficient). Highly expended clones were detected in 15/182 patients, whereas 43/182 revealed no clonal enrichment. A low TCR clone evenness (high Gini coefficient) was significantly more frequent in normal lung areas than in the corresponding tumor areas (n=20, p=0. 02). In the cancer tissue, a high Gini index further correlated with high tumor mutational burden, indicating neoantigen-induced T cell clone expansions. Correspondingly, high TCR clonality was associated with an inflamed tumor phenotype associated with PD-1+ immune cells, CD3+, CD8A+, CD163+, and CD138+ cells, as well as higher expression of genes connected to immune activation (PRF1, GZMB, GZMH) and T cell exhaustion (PD-L1, LAG3, TIGIT). Cancer tissue with dominant T-cell clones also showed higher numbers of mature tertiary lymphoid structures with germinal centers. In situ sequencing suggested a close spatial relation between specific T cell clones and tumor cells. Finally, NSCLC patients with dominant T-cell clones showed strong responses and longer survival when treated with immune checkpoint inhibitors. This suggests that TCR clonality analysis is a strong candidate for precision diagnostics. Plausibly, the dominant clones found in NSCLC are responsible for a specific but malfunctioning anti-tumor response that can be unleashed by immune checkpoint inhibition. Citation Format: Hui Yu, Anastasia Magoulopoulou, Masafumi Hori, Amanda Lindberg, Max Backman, Hans Brunström, Millaray Marincevic Zuniga, Johanna Mattsson, Akira Saito, Karin Leandersson, Mats Nilsson, Rose-Marie Amini, Patrick Micke, Carina Strell. Large scale, transcriptome-based analysis of TCR clonality reveals functional immunity in 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 1516.