Programmed Death-Ligand 1 Immunohistochemical Expression in Invasive Urothelial Carcinoma of the Bladder: Association with Lymphovascular Invasion

Abstract

 Introduction: Invasive urothelial carcinoma of the urinary bladder is a heterogeneous malignancy with variable biological behavior and clinical outcomes. Programmed death-ligand 1 (PD-L1) immunohistochemical expression has been widely investigated as a potential biomarker in urothelial carcinoma; however, its clinicopathological significance remains inconsistent.

Materials and Methods: This analytical cross-sectional study evaluated the clinicopathological characteristics of invasive urothelial carcinoma of the bladder and analyzed their association with PD-L1 immunohistochemical expression. A total of 32 formalin-fixed, paraffin-embedded tissue samples diagnosed over a three-year period were included. The variables assessed comprised age, sex, lympho-vascular invasion, perineural invasion, tumor-infiltrating lymphocytes, and histological subtypes based on the WHO Classification of Urinary and Male Genital Tumours, 5th edition (2022). PD-L1 immunohistochemistry was performed using a monoclonal rabbit anti-human PD-L1 antibody (GeneAb™; 1:100 dilution), with tonsil tissue used as a positive control. PD L1 expression was evaluated using the Combined Positive Score (CPS), and a CPS of ≥10 was considered positive.

Results: PD-L1 expression was identified in 3 of 32 cases (9.4%). A statistically significant association was found between PD-L1 expression and lympho-vascular invasion (p = 0.033). No significant association was observed between PD-L1 expression and tumor-infiltrating lymphocytes or other clinicopathological parameters.

Conclusion: PD-L1-positive cases in this study were identified only in tumors with lympho-vascular invasion. However, because of incomplete clinical staging data and the limited sample size, the clinical significance of this observation remains uncertain and requires further validation in larger studies.