High-dimensional longitudinal immune profiling uncovers a dual role of the CXCL9/CXCR3, CXCL13/CXCR5, and CCL11/CCL3 axis in the coupling of immune-related adverse events to immune checkpoint inhibitor response.

2512 Background: Additional characterization is required to understand the immune network signatures and immunophenotypes that link immune-related adverse events (irAEs) to immune checkpoint inhibitor (ICI) therapy responses in cancer patients. Methods: A comprehensive immune profiling analysis was conducted on whole blood and peripheral blood mononuclear cells (PBMC) from 165 oncology patients with various irAEs, including colitis (n=64), myocarditis (n=19), pneumonitis (n=25), arthritis (n=24), and cytokine release syndrome CRS (n=33), and compared to a cohort of 219 cancer patients prior to ICI treatment. Results: Following ICI therapy on cycle 2 day 1 (C2D1), we observed significant increases in IL-6, CCL2, CXCL9, CXCL10, and CXCL13 levels preceding irAEs. CXCL9 was specifically upregulated during the development of colitis, arthritis, CRS, and myocarditis, while CXCL13 increased only in CRS, and CCL3 only in myocarditis and CRS, with no CCL11 upregulation in any irAE. High levels of CXCL9, high CCL11 and low CXCL13 strongly correlated with improved oncologic outcomes in different irAEs. Compared to other cluster, in the high CXCL9 cluster, 5-year overall survival (OS) was significantly improved (HR = 10.26 95% CI, 1.27-82.82, p = 0.029) in colitis (n=20), in CRS (n=21) (HR = 6.45 95% CI, 1.60-25.99, p = 0.009), and in arthritis. In the high CCL11 cluster, 5-year OS was significantly improved in pneumonitis (n=15), (HR = 4.04 95% CI, 1.05-15.46). Conversely, in myocarditis, the high CXCL13 cluster (n=9) was associated with decreased 2-year OS (HR = 6.05 95% CI, 1.03-35.48, p = 0.046). It is important to note that the CXCL9-driven immunophenotypes were characterized by low IL-6. Notable observations include CD38 upregulation and large-scale activation of CD8 memory subsets during ICI therapy, concomitant with increased circulation of immature neutrophils at the onset of irAEs diagnosis. This event may increase the migration of TCRγδ, NK, DC, and CD8 cells to tumor sites through CXCR3/CXCL9 interactions. Conclusions: This study unravels intricate connections between immune activation and tumor response. CXCL9, CCL11, and CXCL13 emerge as pivotal biomarkers bridging the gap between ICI therapy effectiveness and distinct irAEs-associated immunophenotypes.