Search

Urothelial carcinoma (UC) is the most common form of bladder cancer. Although the 5-year overall survival rate of bladder cancer is 73%, the outcome for patients with metastatic UC remains poor. Programmed death ligand 1 (PD-L1) is over-expressed by many cancers and facilitates tumour evasion of host immune responses via the PDL1/PD-1 checkpoint. Immunotherapy is an emerging paradigm for the treatment of advanced UC with recent clinical trials demonstrating significant responses in patients by blocking PD-1/PD-L1. Nonetheless, the data on the prevalence of PD-L1 in urothelial tumours is limited. The goal of this study was to evaluate the prevalence of PD-L1 expression in tumour-infiltrating immune cells (IC) in UC in Canada and to correlate its expression with multiple clinical and pathological parameters. Three hundred archived UC specimens from six Canadian sites were assessed for PD-L1 expression using the Ventana PD-L1 (SP142) immunohistochemistry assay. The presence of discernible PD-L1 signal in tumour-infiltrating IC involving >5% of tumour with associated stroma was deemed "positive" and was observed in 39% (CI 33.13-44.43%) of specimens tested. There was no relationship between positivity of the PD-L1 assay and several clinicopathological parameters, including age, gender, and tumour location. Notably, PD-L1 expression of tumourinfiltrating IC exhibited a significant association with tumour stage (p=0.0409), with a trend towards higher PDL1 positivity in more advanced tumours. In conclusion, PD-L1 expression in tumour-infiltrating IC is common in UC in Canada and may be associated with more advanced stage cancers, reinforcing that PD-L1 may be a relevant therapeutic target for UC. [ABSTRACT FROM AUTHOR]