Relevance between PD-L1 expression combined with tumor infiltrating lymphocytes and prognosis in advanced hypopharyngeal squamous cell carcinoma.

Abstract

e17528 Background: Little information has been available regarding immune-related prognostic factors in patients with advanced hypopharyngeal squamous cell carcinoma (HPSCC). Expression of programmed cell death-ligand 1 (PD-L1) in tumor cells is known to be a mechanism whereby cancer can escape immune surveillance. We investigated the predictive relevance of PD-L1 expression in tumor cells and tumor-infiltrating lymphocyte (TIL) density in patients with locally advanced HPSCC receiving neoadjuvant chemotherapy (NAC). Methods: We retrospectively reviewed 83 consecutive patients with advanced HPSCC who had received NAC. PD-L1 expression and TIL density were evaluated by immunohistochemical analysis. Results: Univariate and multivariate analyses demonstrated that CD8+ TIL density was an independent and significant predictive factor for progression free survival (PFS) and overall survival (OS), whereas PD-L1 expression was not correlated with PFS or OS. Subgroup analysis defined by PD-L1 expression in combination with CD8+ TIL density revealed that the PD-L1-/CD8high group showed the longest survival (median PFS and OS were not reached), whereas the PD-L1+/CD8low group showed the shortest PFS (median 7.9 months, p = 0.006) and OS (14.3 months, p = 0.011) by Kaplan-Meier curves. Conclusions: Although there was no significant correlation between PD-L1 expression and prognosis in stage III and IV HPSCC patients who received NAC, the subgroup analysis indicated that combination of lack of PD-L1 expression and higher CD8+ TIL density was significantly associated with favorable survival in these patients. These results suggested that PD-L1 expression levels in combination with CD8+ TIL density could be a useful predictive biomarker in patients with stage III and IV HPSCC.