Head and Neck Cancer

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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.

Ping Ai, MD, PhD

Biography:
Ai Ping, MD,PhD. Associate professor of Oncology Center of West China Hospital, Sichuan University, Chengdu, China. Clinical work mainly focuses on radiotherapy, chemotherapy, and targeted therapy for head and neck carcinoma. Research areas include biomarker development of head and neck carcinoma, radiation sensitivity, and tumor microenvironment of different histological subtypes.

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