The change of soluble programmed cell death ligand-1 (sPD-L1): A new predictor of prognosis in hypopharyngeal squamous cell carcinoma patients treated with radiotherapy

PurposeThe aim of this study was to evaluate the concentration of soluble programmed cell death ligand-1 (sPD-L1) in the plasma of hypopharyngeal squamous cell carcinoma (HSCC) patients before and after radiotherapy (RT) and to explore its correlation with prognosis.MethodsA total of 47 patients and 12 healthy individuals were enrolled. All blood samples were collected before RT and 35 blood samples were obtained after RT. Twenty-three matched Formalin-fixed paraffin-embedding (FFPE) specimen from patient tumor biopsies were examined PD-L1 immunohistochemistry, and the sPD-L1 levels were quantified by enzyme-linked immunosorbent assay (ELISA).ResultsThe level of plasma sPD-L1 in patients were higher than healthy individuals. Plasma sPD-L1 level at diagnosis correlated positively with T stage. The plasma sPD-L1 concentration had moderate correlations with PD-L1 expression in tissue (tPD-L1). In addition, the study proved that patients with high sPD-L1 had significantly worse overall survival (OS) than patients with low sPD-L1. sPD-L1 levels before RT was the unique independent prognostic factors for OS.ConclusionsThe study reported that sPD-L1 concentration before RT is proportional to the expression of tPD-L1. Besides, sPD-L1 before RT and tPD-L1 may serve as useful biomarkers for prognosis.