PD-L1 Expression Confers Better Prognosis in Locally Advanced Oral Squamous Cell Carcinoma

Clinical trials with therapies targeting immune checkpoint molecules have shown promising results in several tumor types. However, the predictive and prognostic values of these immunological factors for locally advanced oral squamous cell carcinomas (LAOSCC) remain unclear. Our purpose was to evaluate the expression and prognostic value of programmed cell death-ligand1 (PD-L1) and PD-L2 and to correlate their expression with the degree of infiltration by CD8 cells in LAOSCC. A total of 84 patients with LAOSCC were included. PD-L1, PD-L2 and CD8 expression was detected in the tumor tissue using immunohistochemistry and was tested for correlation with clinical outcome. PD-L1 and PD-L2 were expressed in 52.4% and 23.8% of LAOSCC cases, respectively. PD-L1 positivity was significantly associated with superior disease-free (p=0.024) and overall (p=0.008) survival of the patients and retained significance in multivariate analysis. PD-L1 positivity was correlated with CD8 density. PD-L1 expression was associated with CD8 tumor-infiltrating lymphocytes and better outcome in patients with LAOSCC.