Upregulation of PD-L1 and PD-L2 in neck node metastases of head and neck squamous cell carcinoma.

Abstract

This study aimed on evaluating the expression levels of the immune checkpoint proteins, PD-L1 and PD-L2, in tissue specimens of 175 oral squamous cell carcinomas (OSCC) and 33 corresponding lymph node metastases (LNM). Tissue microarrays of primary OSCC and matched LNM were investigated via immunohistochemistry regarding PD-L1/PD-L2 expression. Results were compared for primary tumors and corresponding metastases and correlated with clinicopathological data. PD-L1 expression in cancer cells correlated significantly with tumor size, and the presence of regional metastases (P < 0.01). PD-L1 expression was significantly higher in metastases as compared to primary OSCC (P < 0.05). Overall survival was significantly worse in patients with higher levels of PD-L1 and PD-L2 score (P < 0.05). This is the first publication to compare PD-L1 and PD-L2 expression in primary OSCC and matched LNM. The results indicate that anti-PD-1 therapy may be of therapeutic use even in early stage OSCC to prevent further progression.