Study of the PD-L1 expression, T-cells density and immunoscore in paired baseline tumor biopsies and surgical specimens in squamous cell carcinoma of the oral cavity.

ABSTRACT

OBJECTIVES: Primary objective was to evaluate the correlation between immune marker expression in baseline tumor biopsies and their respective surgical specimens in squamous cell carcinoma of the oral cavity (OCSCC). Secondary objective was to assess the impact of these markers on overall (OS) and disease-free survival (DFS). MATERIALS AND METHODS: Patients with a histological diagnosis of oral squamous cell carcinoma treated surgically between 2012 and 2020 were included in this retrospective, translational monocentric study. The expression of PD-L1, T-cells markers and an OCSCC-adapted immunoscore were evaluated by multiplex immunohistochemistry. RESULTS: One hundred and four patients (mean 58 years) were included. Seventy patients had paired samples available. Poor correlation was highlighted for PD-L1-positive surface expression (r = 0.29) and combined positive score (CPS). For CPS ≥ 20 and CPS ≥ 1, correlation coefficient r was 0.24 and 0.46 respectively. T-cells density showed also poor correlation with a r of 0.57 and 0.31 for CD3 and CD8 T-cells, respectively. Univariate survival analyses showed significant better OS and DFS (P < 0.05) for patients with stage III-IV OCSCC with a high compared to a low immunoscore, based on surgical samples only. CONCLUSION: Our study showed poor correlation in PD-L1 expression, CPS, T-cells density and immunoscore between baseline tumor biopsies and surgical resection specimens. In addition, the immunoscore may emerge as a potential prognostic factor in advanced squamous cell carcinoma of the oral cavity. If surgical specimens are available, they may be of interest for clinical practice decision.