The immune microenvironment in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignant neoplasms across the world. Curative surgery can be considered in Resectable disease in absence of high-risk features, as the presence of large regional lymph nodes. In surgical patients, lymphnodal involvement (LNI) still represents the most relevant prognostic factor for long-term oncological outcomes. Nevertheless, despite recent technological advancements, PDAC preoperative radiological nodal staging still lacks sensitivity. Aim of this study was to determine immune markers, expressed by tumor microenvironment (TME), as potential preoperative predictors of LNI. Retrospective clinical-pathological data of patients with diagnosis of PDAC undergone pancreatic surgery were analyzed. Immunohistochemical (IHC) staining using tissue microarray forPD-L1, CD3, CD4, CD8, FOXP3, CD20, iNOS and CD163 was performed in order to characterize the TME of eache patient. A total of 45 patients were analyzed. Our data have shown that the number of iNOS+ and CD163+ macrophages in the tumor compartment and CD8/CD3 lymphocytes ratio were directly correlated with metastatic lymphnodes. TME could potentially provide immune markers predictive of LNI and can therefore be considered as an aid in staging and thus in the subsequent choice of the best treatment pathway.