Associations among pretreatment tumor necrosis and the expression of HIF-1α and PD-L1 in advanced oral squamous cell carcinoma and the prognostic impact thereof

Objective: The treatment strategies for advanced oral squamous cell carcinoma (OSCC), especially with necrotic changes, are not effective. The programmed death ligand 1 (PD-L1) immune escape may be one of the underlying sources of resistance. Furthermore, anti-PD-L1 directed immunotherapy may be another choice for adjuvant therapy. Therefore, the expression of PD-L1 in advanced OSCC with necrotic changes is very important. Materials and methods: A total of 218 eligible patients with advanced stage (stage III/IV) OSCC and neck metastasis were enrolled. The presence of necrosis was reviewed by pretreatment magnetic resonance imaging. Paired paraffin-embedded primary tumor and metastatic lymph nodes (LN) sections were stained with antibodies against hypoxia-inducible factor-1 alpha (HIF-1 alpha) and PD-L1. Moderate-to strong HIF-1 alpha nuclear staining in >10% and cell surface PD-L1 expression in >5% of OSCC cells were recorded as a positive result. Results: For advanced OSCC with necrotic changes, there was substantial agreement in primary tumor (kappa value 0.54) and almost perfect agreement in metastatic LN (kappa value 0.86) between HIF-1 alpha and PD-L1 expression. The patients with both necrosis and positive PD-L1 expression in OSCC surrounding necrosis had worse disease control and survival outcomes. After multivariate analysis, metastatic LN necrosis and positive PD-L1 expression were found to be significant independent adverse factors. Conclusion: Advanced OSCC patients with both necrosis and positive PD-L1 expression in OSCC surrounding necrosis had worse outcome. The aggressive behavior of advanced OSCC could be partially related to PD-L1 immune escape. These patients may be good candidates for anti-PD-L1 immunotherapy. (C) 2015 Elsevier Ltd. All rights reserved.