Head and Neck Cancer
PV QA 2 - Poster Viewing Q&A 2
MO_33_2774 - High PD-L1 expression predicts metastasis in nasopharyngeal carcinoma
Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3
High PD-L1 expression predicts metastasis in nasopharyngeal carcinoma
X. Li1, Y. Jiang2, S. Zhao2, H. Zhang1, X. Peng1, and P. Ai1; 1State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China, 2Department of Pathology,West China Hospital, Sichuan University, Chengdu,Sichuan, China
Purpose/Objective(s): Programmed death-ligand 1 (PD-L1) plays an important role in T cell tolerance and tumour immune escape, which has been reported to be a prognostic factor in various malignancies. However, only a few studies about PD-L1 in nasopharyngeal carcinoma (NPC) are available, and the reported prognostic role of PD-L1 in NPC patients remains controversial. In this study, we aimed to investigate the alterations of PD-L1 expression on tumour cells in NPC patients with and without metastasis. Furthermore, we would explore the correlation of PD-L1 expression on tumor cells and serum Epstein-Barr virus (EBV) DNA load.
Materials/Methods: Pathologically confirmed NPC treated with intensity-modulated radiation therapy were recruited for the study. Formalin-fixed, paraffin-embedded tissues were studied by immunohistochemistry staining. The expression of PD-L1 on tumour cells was detected and the staining results were evaluated by positive tumour cell percentage. Clinical characteristics and qRT-PCR data of serum EBV DNA load before treatment were collected. The optimal cut-off value for PD-L1 staining was determined by the area under the curve of the receiver operating characteristic (ROC). The Chi-square test was used to evaluate results with SPSS 25.0.
Results: 78 patients were included in this study, with median follow up 52.8 months (range 12-108 months). The median age was 44 years old (range 22 –65 years). Among those 78 patients, 43(55%) patients had metastasis, 35 (45%) didn’t have metastasis. PD-L1 expression on tumour cells was detected in 66 patients (66/78, 85%). When staining with PD-L1 on >45% tumor cells, PD-L1 expression was classified as being at a high level according to the ROC curve analysis. In metastasis group, 25 out of 43 patients showed high PD-L1 expression, while in non-metastasis group only 7 out of 35 patients showed high PD-L1 expression (p=0.001). We observed that more patients in metastasis group had detectable serum EBV DNA load than non-metastasis group (p=0.007). In order to study the effect of EBV on PD-L1 expression, we explored the correlation of PD-L1 expression on tumor cells and serum EBV DNA status (before treatment). Our data showed that PD-L1 expression was not significantly correlated with EBV DNA load among all the patients (p= 0.554).
Conclusion: Our results revealed that PD-L1 might be a potential metastatic biomarker for NPC patients. Furthermore, EBV status was not significantly correlated with PD-L1 expression. PD-1/PD-L1 pathway might be a promising therapy target for advanced NPC.
Author Disclosure: X. Li: None. Y. Jiang: None. S. Zhao: None.