Prognostic role of programmed death ligand 1 (PD-L1) and the immune microenvironment in laryngeal carcinoma

Objectives: The immune system is crucial in the evolution of head and neck cancer. Programmed cell death ligand 1 (PD-L1) seems to rely on close relations between neoplastic cells and immune cells in the tumor microenvironment. The main aim of this study was to apply univariate/multivariate analysis to investigate the prognostic significance of PD-L1, tumor-infiltrating lymphocytes (TILs), and tertiary lymphoid structures (TLS) in laryngeal carcinoma (LSCC). Materials and methods: PD-L1 (in terms of combined positive score [CPS]), TILs and TLS were assessed at pathology on 70 consecutive samples of LSCC. Results: A CPS >= 1 coincided with a lower recurrence rate (RR) (p = 0.007) and longer disease-free survival (DFS) than a CPS < 1 (p = 0.0027). Cases with higher TIL counts showed a lower RR (p = 0.036) and longer DFS than those with lower TIL counts (p = 0.0062). Cases revealing TLS had a lower RR (p = 0.004) and longer DFS (p = 0.0034) than those with no TLS. On multivariate analysis, the presence of TLS retained its positive prognostic value (p = 0.024), while CPS remained significant as regards disease recurrence (p = 0.050). Conclusions: PD-L1 seems to be an indirect marker of effective anti-tumor response in LSCC, possibly being expressed as a result of a greater immune pressure on cancer cells. The presence of TLS emerged as a positive prognostic factor. Further prospective studies are needed to characterize the role of PD-L1 as a marker of antitumor immune response and prognostic factor in LSCC, also with regard to the effectiveness of immunotherapeutic protocols.