Tumor-infiltrating OX40 lymphocytes is an independent positive prognostic factor for patients with pancreatic ductal adenocarcinoma.

PURPOSE

OX40 signaling pathway occupies a vital place in anti-tumor immunity; however, the role of tumor-infiltrating OX40 lymphocytes in pancreatic ductal adenocarcinoma (PDAC) remains to be identified.

METHODS

A total of 325 sequential PDAC patients who received curative tumor resection between January 2014 and December 2016 were enrolled. Tissues of these patients were immunohistochemically assessed for tumor infiltration of CD4 T cells, CD8 cytotoxic T cells (CTLs), and OX40 lymphocytes. The frequency of OX40 tumor-infiltrating lymphocytes (TILs) was then analyzed to various clinicopathological features, densities of tumor infiltration of CD4 T cells and CTLs, and survival analysis was conducted using Kaplan-Meier (KM) curves. The risk scores of associated markers were calculated by the Cox proportional-hazards model.

RESULTS

Our results showed that higher OX40 lymphocytes infiltration was significantly correlated with superior median overall survival (OS) (25.8 vs 13.4 months, P < 0.001). Additionally, using univariate and multivariate Cox proportional hazards analyses, this study revealed that together with tumor differentiation, tumor size, serum CA199 levels, serum CA125 levels, and the infiltration of intratumoral CD8 T cells. The abundance of OX40 lymphocytes within the tumor was continued to be an independent predictor for OS (P = 0.023, HR = 0.713, 95% CI: 0.532-0.954).

CONCLUSIONS

This study demonstrated that intratumoral infiltration by a high number of OX40 lymphocytes is a novel biomarker for favorable prognosis in resected PDAC patients, which implies that OX40-agonist-based immunotherapy might be a potential target in PDAC patients.