Analysis of Epstein-Barr Virus (EBV) and PD-L1 Expression in Nasopharyngeal Carcinoma Patients in a Non-Endemic Region.

Background: The purpose of this study was to evaluate the status of Epstein-Barr virus (EBV) infection and the expression of programmed cell death ligand-1 (PD-L1) in tumor samples from patients with nasopharyngeal carcinoma (NPC).

Methods: Evaluation of EBV infection was performed through the detection of EBV-encoded small ribonucleic acids (EBER) by in situ hybridization, and PD-L1 expression was performed through immunohistochemistry.

Results: In total, 124 samples were evaluated for EBER and 120 for PD-L1 expression. A total of 86.3% of cases were positive for EBER and 55.8% were positive for PD-L1. There was a correlation between EBER positivity and the presence of undifferentiated carcinoma histology ( = 0.007) as well as the absence of tobacco history ( = 0.019). There was a correlation between PD-L1 expression and EBER positivity ( = 0.004). There was no statistically significant difference between overall survival (OS) and EBER ( = 0.290) or PD-L1 ( = 0.801) expression.

Conclusions: This study corresponds to one of the largest cohorts of NPC in a non-endemic region. Phase III studies with checkpoint inhibitors are ongoing and may provide more data about the role of PD-L1 expression in this disease.