Analysis Of Associations Of Cxcr3 Ligands With Immune Microenvironment And Aggressiveness In Murine And Human Pancreatic Ductal Adenocarcinoma

762 Background: The complex milieu of cytokines within pancreatic ductal adenocarcinoma (PDAC) promotes tumor progression and immune suppression thereby contributing to the dismal prognosis of patients with PDAC. However, the roles of many cytokines, including CXCR3 ligands, in PDAC have not been thoroughly investigated. Methods: Bioinformatics analyses of PDAC microarray and TCGA datasets were used to identify cytokines overexpressed in PDAC, their association with patient survival as well as the expression of cognate cytokine receptors. Comparative analysis of cytokine expression in KrasLSL-G12D-P53LSL-R172H-Pdx1-Cre (KPC) and KrasLSL-G12D-Pdx1-Cre (KC) murine PDAC models were used to validate these findings. Pathway and CIBERSORT analyses were employed to determine mechanistic basis of altered survival associated with cytokines of interest. Results: Of the 149 cytokines analyzed, CXCR3 ligands CXCL9 and CXCL10 were highly and consistently overexpressed in PDAC datasets. Concurrently, CXCL9, CXCL10 and PF4 were overexpressed in the aggressive KPC murine model compared to the indolent KC model. CXCR3 showed robust expression in PDAC in microarray, TCGA and IHC analyses. Interestingly, high expression of CXCR3 ligands was associated with shorter overall survival (p = 0.04 for CXCL9, 10 and 11 and p = 0.02 for PF4) while high expression of CXCR3 was associated with increased overall survival (p = 0.03). Pathway analysis of genes correlated with CXCR3 and/or its ligands showed that CXCR3 ligands may promote T-cell exhaustion (p < 0.001). Finally, CIBERSORT analysis of TCGA data demonstrated that high CXCR3 expression was associated with increased CD8 T-cell and naïve B-cell signatures and loss of plasma cells signatures. High CXCR3 ligand expression was associated with increased CD8 T-cell, and M1 macrophage, and loss of NK-cell signatures(p < 0.05). Conclusions: CXCR3 ligands are overexpressed in PDAC and are associated with poor survival, likely related to alterations in tumor immune infiltrate/activity and may represent targets to augment anti-tumor immunity.