Prognostic and predictive value of EZH2 expression and the tumor immune microenvironment in Merkel cell carcinoma.

Abstract

Merkel cell carcinoma (MCC) is a rare and lethal type ofskin cancer characterized by frequent recurrences and metastases. In view ofthe lack ofa proven treatment option for MCC, we immunochemically evaluated the presence ofMerkel cell polyomavirus (MCPyV), PD-1, PD-L1, CD8, and EZH2 on slides prepared from tumor tissues of13 patients with MCC, and examined their association with disease progression and overall survival. PD-1 was expressed on tumor infiltrating lymphocytes (TILs) in 92.3% ofthe patients. None ofthe tumor cells expressed PD-L1. CD8 levels were higher in MCPyV-positive tumors. Interestingly, higher CD8 levels correlated with better overall survival (p=0.025), while higher EZH2 expression correlated with metastasis/recurrence (z=-1.396, p=0.089). However, low EZH2 expression was associated with poor overall survival (χ2=3.745, Cramer V=0.537, p=0.086). These findings suggest that EZH2 plays a significant role in MCC and may be a promising therapeutic target.