FOLFIRINOX regulated tumor immune microenvironment to extend the survival of patients with resectable pancreatic ductal adenocarcinoma

Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the most deadly malignant tumors worldwide due to its ineffective diagnosis and poor prognosis. The longest median overall survival (OS) to PDAC patients has been provided by FOLFIRINOX. It is essential to identify the mechanisms of FOLFIRINOX to gain new insights for the treatment of PDAC. Methods: We compared gene expression levels of PDAC patients who received neoadjuvant FOLFIRINOX prior to surgery with those of patients who received no neoadjuvant chemotherapy. Bioinformatics analysis was applied to screen differentially expressed genes (DEGs). Three microarray data sets were downloaded to analyze gene expression data between PDAC and adjacent non-tumor tissues. Overlapping DEGs were subjected to Kaplan-Meier survival analysis. The genes relating to poor outcomes and would be decreased after FOLFIRINOX were input into the Oncomine, University of Alabama Cancer (UALCAN), and LinkedOmics databases to analyze the gene expression and regulation networks. Results: A total of 83 differentially expressed genes (DEGs) were screened and subjected to bioinformatics analysis, which indicated FOLFIRINOX influenced the immune microenvironment of PDAC. Seventy-three genes significantly associated with the OS of PDAC patients. A Venn diagram revealed CXCL5 and PLAU were related to poor outcomes and would decrease after FOLFIRINOX chemotherapy of PDAC patients. It turned out that CXCL5 participated in the immune response-regulating signaling pathway in PDAC patients. Conclusions: FOLFIRINOX regulated tumor immunity by reducing expression of the immunosuppressive gene CXCL5, laying a foundation for further study of combination therapy of FOLFIRINOX and immunotherapy.