Expression of PD-L1 in tumor and immune system cells affects the survival of patients with urinary bladder cancer

Background: The prediction of tumor malignancy is still one of the most demanding diagnostic tasksin urinary bladder cancer because of its clinicopathological heterogeneity. The aim of this study was toevaluate the expression of PD-L1 in tumor cells (TCs) and immune effector cells (IECs) as well as thepattern of distribution of PD-L1+ IECs within the tumor (dispersed or aggregated) and their associationwith survival of patients with pT1-pT4 urinary bladder cancer.Materials and methods: 110 patients with stage pT1-pT4 urothelial bladder carcinoma who underwentradical cystectomy/cystoprostatectomy between 2011 and 2014 were included in the study. Paraffin blocksmost representative of the tumor were selected for H&E staining as well as immunostaining with the useof rabbit anti-PD-L1 (Ventana clone SP142, Roche). In each sample, the area of the tumor containing PDL1+IECs, as well as, the pattern of distribution (dispersed or aggregated) of PD-L1+ immune effectorcells within the tumor were analyzed. In addition, the expression of PD-L1 in TCs was also assessed.Results: Patients had a shorter survival time in pT2-pT4 cases without TCs expressing PD-L1 (p = 0.007)and/or when PD-L1+ IECs displayed a predominantly dispersed pattern of distribution (p = 0.013).Conclusions: The expression of PD-L1 on TCs and IECs is a prognostic factor which allows for stratificationof patient survival in UBC. The predominance of dispersed or aggregated pattern of distribution ofPD-L1+ IECs in the tumor may be considered as a new prognostic factor in pT1-T4 UBC and indicate thefunctional status of the immune system