Expression of PD-1/PD-L1 in head and neck squamous cell carcinoma and its clinical significance

Objective: To investigate the role of programmed death-1 (PD-1), programmed death-ligand 1 (PD-L1), and P16 in patients with head and neck squamous cell carcinoma (HNSCC). Methods: A total of 95 paraffin-embedded samples of tumorous tissue of HNSCC were collected. Expression levels of PD-1, PD-L1, and P16 were determined by immunohistochemistry. Results: A significantly higher proportion of PD-1 among patients infected with the human papillomavirus was found. PD-L1 expression is closely associated with the primary site of the tumor, postoperative recurrence, survival, PD-1 expression and P16 expression. Univariable analysis indicated that T stage, N stage, tumor node metastasis stage, tumor differentiation, and PD-L1 expression were all shown to be prognostic variables for overall survival in patients with HNSCC. In the multivariate analysis, only N stage (P = 0.010) and PD-L1 expression (P = 0.001) were found to be independent prognostic variables for overall survival. In addition, for disease recurrence, multivariate analysis showed that only PD-L1 expression was the associated independent risk factor. For the patients with negative PD-L1 expression, Kaplan-Meier analysis revealed that they had significantly worse outcomes in terms of overall survival (P = 0.001). Similarly, compared with the patients with positive PD-L1 expression, those with negative PD-L1 expression had a higher probability of recurrence (P = 0.026). Conclusions: The expression of PD-L1, PD-1, and P16 in HNSCC is significantly correlated. Human papillomavirus infection (P16 positive) is negatively related to postoperative recurrence. HNSCC patients with positive PD-L1/PD-1 expression tend to have better overall survival outcomes and lower probability of recurrence, providing more evidence for the PD-l-targeted immunotherapy of HNSCC.