CD44 expression associates with EBV LMP1, reduced CD8⁺ T cell infiltration, and lower PD-L1 combined positive score in nasopharyngeal carcinoma

BACKGROUND: Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV)-associated malignancy characterized by a highly immune-infiltrated yet clinically heterogeneous tumor microenvironment. Iron metabolism has been proposed as a potential determinant of tumor progression and immune regulation. CD44 and transferrin receptor 1 (TfR1) represent two distinct iron uptake pathways, but their relative contribution to EBV-driven NPC and immune modulation remains unclear. METHODS: Sixty-eight NPC biopsies from a Tunisian cohort were analyzed by immunohistochemistry for CD44, TfR1, EBV LMP1, PD-L1, CD8, FoxP3, and CD163. Associations with clinicopathological parameters and immune infiltrates were assessed using chi-square and Spearman correlation tests. RESULTS: High CD44 expression was observed in 48.5% of cases and was significantly associated with lymph node involvement (p = 0.012) and TNM stage (p = 0.042). CD44 expression positively correlated with LMP1 (r = 0.463, p = 0.001). In contrast, CD44 was inversely correlated with CD8⁺ T-cell infiltration (r = - 0.283, p = 0.019) and PD-L1 combined positive score (CPS) (r = - 0.247, p = 0.042). A significant positive correlation was observed between LMP1 and PD-L1 expression, both for tumor proportion score (TPS) (r = 0.341, p = 0.003) and CPS (r = 0.345, p = 0.002). In contrast, TfR1 expression was associated with advanced tumor stage (p = 0.022) but showed no significant relationship with immune parameters or LMP1. CD44 and TfR1 expression were inversely correlated (r = - 0.250, p = 0.040), suggesting alternative iron acquisition pathways. CONCLUSION: Our findings suggest that CD44 may act as a key regulator linking iron metabolism and immune modulation in EBV-associated NPC. Although direct iron measurements were not performed, the observed associations with reduced CD8⁺ T-cell infiltration are consistent with a potential role of CD44 in shaping an immune-restricted tumor microenvironment. These results provide integrative evidence of a CD44-iron-immune axis in a Tunisian NPC cohort and highlight CD44 as a potential prognostic biomarker and therapeutic target.