Evaluation of PD-L1 Expression in Colorectal Carcinoma and its Correlation with Different Clinical-pathological Parameters among Iraqi Patients

Abstract

Background: PD-L1 is a key immune checkpoint transmembrane physiological ligand for programmed-death1 (PD1), the interaction of programmed cell death receptor 1 (PD-1) and programmed death ligand 1 (PD-L1) plays an important role in inhibiting the immune mechanism by which cancer cells can escape antitumor immunity. Immunotherapy using checkpoint inhibitors is a growing treatment modality in many cancers; one such is anti PD1/PD-L1. Objectives: To evaluate the expression of Programmed Death-Ligand 1 (PD-L1) in colorectal carcinoma and determine its association with clinicopathological characteristics, in order to explore its potential role as a predictive marker for immunotherapy. Materials and Methods: PD-L1 antibody retrospectively analyzed immunohistochemically in formalin-fixed paraffin-embedded tissue blocks of 60 specimens with colorectal carcinomas operated between December 2023 - September 2024. A comparison performed between PD-L1 expression in tumor cells (TCs) as well as tumor-infiltrating immune cells (TIICs) for age, sex, size of tumor, histological differentiation, Lymphovascular invasion, the primary tumor location, number of involved lymph nodes, Distant metastasis and AJCC stage. Results: Of the 60 patients, the median age was 62.5 (range: 42–80) years. Sixteen samples were PDL1 positive in TCs, increased to 35% in TIICs. A significant expression of PD-L1 in TCs was correlated with lymphovascular invasion (P=0.002), lymph node metastasis (P= 0.001) and AJCC staging (P=0.001). The PD-L1 status in TIICs was again connected with adverse clinical and pathological parameters. Conclusions: The expression of PD-L1 in TCs and TIICs is associated significantly with advanced cancer or lymphatic invasion in patients who underwent surgery after a diagnosis of CRC. The research designates the significance of estimation of TCs and TIICs in correlation to clinical-pathological characteristics of patients a finding that could produce a piece of evidence for precise electing immunotherapy.