Programmed Death-Ligand 1 Expression and Tumor-Infiltrating Lymphocytes in Temporal Bone Squamous Cell Carcinoma.

Abstract

The tumor immune microenvironment in temporal bone squamous cell carcinoma (TBSCC), including the programmed death-ligand 1 (PD-L1) expression and tumor-infiltrating lymphocytes (TILs), has not been established. Retrospective cohort study. We performed immunohistochemistry analyses to retrospectively analyze 123 TBSCC cases for PD-L1 expression and TILs and their prognostic significance. We also evaluated the prognostic correlations between these immunomarkers and the therapeutic responses to chemoradiotherapy (CRT). PD-L1 expression (≥1%) was detected in 62 (50.4%) TBSCC cases and was significantly associated with worse prognosis: progression-free survival (PFS), P < .0001; overall survival (OS), P = .0009. A high density of CD8⁺ TILs was significantly associated with better prognosis (PFS, P = .0012; OS, P = .0120). In contrast, a high density of Foxp3⁺ TILs tended to be associated with an unfavorable prognosis (PFS, P = .0148; OS, P = .0850). With regard to the tumor microenvironment subtypes defined by CD8⁺ TILs and PD-L1 expression, the CD8^low /PD-L1⁺ group showed significantly worse prognosis. Among the 36 neoadjuvant CRT-treated cases, PD-L1 expression was significantly associated with worse OS (P = .0132). Among the 32 CRT-treated cases without surgery, a high density of CD8⁺ TILs tended to be more highly associated with complete response to CRT compared to a low density of CD8⁺ TILs (P = .0702). These results indicate that the evaluation of the tumor immune microenvironment may contribute to the prediction of prognoses and the selection of an individualized therapeutic strategy for patients with TBSCC. 4 Laryngoscope, 131:2674-2683, 2021.