Programmed death ligand-1 (PD-L1) expression in serous ovarian carcinoma with clinicopathological associations

Background and objectives The prevalence and significance of programmed death-1 ligand (PD-L1) expression in serous ovarian carcinoma are not well established. This study aimed to evaluate PD-L1 expression using immunohistochemistry (IHC) in whole tissue sections of serous ovarian carcinoma and to correlate its expression with relevant clinicopathological characteristics. Methods A retrospective study of 30 cases was conducted at a tertiary care centre in New Delhi, India, over one yr. All cases were reviewed using HandE staining, and IHC for PD-L1 was performed manually on poly-L-lysine-coated slides using the PD-L1 (E1L3N®) XP® Rabbit monoclonal antibody. Additional clinicomorphological data were recorded and analysed. Results Based on the combined positive score (CPS) with a 1% cutoff, PD-L1 expression was observed in 33% of cases. PD-L1 expression demonstrated a positive correlation with higher FIGO stage and the presence of tumour-infiltrating lymphocytes (TILs) (P=0.029). Interpretation and conclusion PD-L1 may serve as a potential prognostic marker in serous ovarian carcinoma. Its expression could help identify patients who may benefit from targeted PD-L1-based therapies and contributes to a better understanding of the biological behaviour of ovarian carcinoma.