Expression of PD-1 and PD-L1 in patients with stage Ⅳa nasopharyngeal carcinoma and its clinical significance / 中华放射肿瘤学杂志

ABSTRACT

Objective To measure the expression levels of PD-1 and PD-L1 in the tumor tissues of patients with nasopharyngeal carcinoma ( NPC) and to explore the association of their expression with the clinical characteristics and prognosis of NPC patients. Methods The expression levels of PD-1 and PD-L1 in 65 NPC patients were determined by immunohistochemistry, and an analysis was performed on the association of their expression with clinical characteristics and long-term survival in NPC patients. Comparisons between groups were made by the chi-square test or Fisher′s exact test, and the Pearson' s test was used for correlation analysis. Survival rates were calculated using the Kaplan-Meier method, and the log-rank test was used for survival comparison and univariate prognostic analysis. The Cox model was used for multivariate prognostic analysis. Results Expression of PD-1 and PD-L1 was observed in 88%(57/65) and 89%( 58/65) of tumor cell surfaces using a cut-off value of 5%, and 38%( 25/65) and 58%( 38/65) using a cut-off value of 10%. PD-1 expression was significantly correlated with PD-L1 expression using the cut-off value of 5%( P=0003) , and a non-significant correlation was found between the expression levels of PD-1 and PD-L1 using the cut-off value of 10%(P=0080). There was no significant association between the positive expression rates of PD-1 and PD-L1 and clinicopathological characteristics ( P>005 ) . The univariate and multivariate survival analyses showed that using the cut-off value of 10%, the patients with positive PD-L1 expression had significantly reduced progression-free survival ( hazard ratio [ HR]=273, 95% confidence interval [ CI]107-697, P=0035 ) and overall survival ( HR=395, 95%CI109-1427, P=0036) compared with those with negative PD-L1 expression. Conclusions PD-1 and PD-L1 are highly expressed in NPC tissues. The expression of PD-L1 is associated with the poor prognosis in patients with stage IVa NPC, and PD-L1 can better predict the poor prognosis using the cut-off value of 10%.