Programmed death-ligand 1 expression in Epstein-Barr virus positive nasopharyngeal cancer

Nasopharyngeal cancer (NPC) is common in Saudi Arabia; Most cases are related to the Epstein-Barr virus (EBV), which is associated with treatment failure and a high recurrence rate. Programmed cell death protein 1 (PD-1) and Programmed death-ligand 1 (PD-L1) inhibitors emerged as breakthroughs in cancer treatment, including head and neck cancers. The benefit of these therapies was seen in patients with high expression of PD-L1, which is unknown in our population.  We aim to assess PD-L1 expression in EBV-related NPC patients presented to King Fahd Medical City (KFMC). We identified 41 cases of EBV-related NPC diagnosed between 2016 and 2019. PD-L1 expression was assessed using the Tumor Proportion Score (TPS) and Combined Positive Scores (CPS). Results showed that PD-L1 expression was negative in 51% and 29% using TPS and CPS scores, respectively. High expression of PD-L1, more than 50%, was seen in 17% using TPS and 22% using CPS. There was no statistically significant correlation between the degree of PD-L1 expression by TPS or CPS and many variables, including gender, comorbidities, BMI, TNM staging, and smoking status. Over a median follow-up of 29.7 months, Kaplan-Meier survival curves did not show a statistically significant difference between all groups of PD-L1 expression for O.S. or PFS; However, there were shorter O.S noted with CPS 1%–9%, log-rank p-value = 0.031. These findings support investigating the role of Immunotherapy, especially in the high expression subgroup. Data for these patients' outcomes and further studies to explore the role of PD-L1 in NPC are needed.