Abstract A009: T cell immune landscape in melanoma patients before and post immune checkpoint blockade treatment

Abstract Immunotherapy based on immune checkpoint blockade (ICB) has revolutionized cancer treatment. Immune cells, especially T cells, play a crucial role in ICB. However, ICB- induced T cell response remains incompletely investigated. Revealing T cell landscape changes caused by ICB could promote the discovery of novel biomarkers with predictive efficacy and toxicity and the potential strategy to improve the therapeutic efficacy while reducing side effects. We used single cell-based sequencing approaches to analyze transcriptome and surface protein of T cells in peripheral blood collected before and post ICB treatment from melanoma patients with immune-related adverse events. A total of 17 cell clusters were identified and annotated according to the expression of RNA and protein. Collectively, variation existed among the recruited participants. ICB treatment decreased the proportion of memory CD4 T cells while increasing the proportion of T follicular helper cells. In summary, these findings provide insight into how ICB modulates T cell responses in melanoma patients. Citation Format: Ying Luo, Chen Yao, Tuoqi Wu. T cell immune landscape in melanoma patients before and post immune checkpoint blockade treatment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr A009.