Programmed cell death ligand 1 (PD-L1) is an immune checkpoint inhibitor that is a transmembrane glycoprotein belonging to the B7/CD28 co-stimulatory family. By binding to the programmed death-1 (PD-1) receptor on T lymphocytes, PD-L1 downregulates immune responses by inducing T-cell apoptosis and functional exhaustion, thereby allowing tumour cells to evade immune surveillance. The PD-1/PD-L1 signalling axis plays a critical role in tumour immune escape, and therapeutic blockade of this pathway has been shown to restore antitumor immunity, leading to significant clinical benefit in several malignancies, including urothelial carcinoma.

PD-L1 expression has been associated with more aggressive clinical features, increased recurrence rate and reduced overall survival in patients with urothelial carcinoma. However, other studies have concluded that there is a positive relation between PD-L1 expression and favourable outcome of the disease.

Given the conflicting evidence regarding the prognostic role of PD-L1 in urothelial carcinoma of the urinary bladder which remains controversial, it is important to further define its prognostic relevance.

Hence, this study is being undertaken to evaluate the correlation of PD-L1 expression with prognosis in patients with urothelial carcinoma of the urinary bladder and further support the need for development of newer immune checkpoint inhibitors.