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

Abstract

Objectives/Hypothesis: 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.Study Design: Retrospective cohort study. Methods: 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).Results: 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).Conclusions: 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.

Temporal Bone Squamous Cell Carcinoma: Molecular Markers Involved in Carcinogenesis, Behavior, and Prognosis: A Systematic Review

“…In selected recurrent or metastatic head and neck SCC cases, treatments with anti-programmed cell death-1 (PD-1) immune check-point inhibitors showed more favorable prognoses compared to treatment with conventional chemotherapies or cetuximab [58,59]. Nevertheless, TBSCC was not included in those clinical trials, nor has its immune microenvironment been sufficiently studied; however, Hongo et al [1] analyzed a cohort of 123 TBSCC patients. In their series, the PD-L1 membrane expression of tumor cells was assessed in ≥100 tumor cells, and samples were defined as "positive" when membranous staining was detected in ≥1% of the tumor cells.…”

“…Temporal bone squamous cell carcinoma (TBSCC) is extremely uncommon, accounting for <0.2% of head and neck squamous cell carcinomas (SCCs) [1]. More frequently, these SCCs originate from the external auditory canal (EAC) and extend into the temporal bone [2].…”

“…Although radiotherapy seems to be an effective adjuvant therapy in advanced cases, its role in low-stage tumors, and as a primary treatment, has yet to be established. The value of chemotherapy is also still unclear [1].…”