Programmed Death-Ligand 1 (PD-L1) expression in triple-negative breast cancer: A cross-sectional study from a Tertiary Diagnostic Laboratory in Pakistan.

Abstract

Objective: To evaluate the frequency of PD-L1 expression by combined positive score (CPS) and analyze the clinic-pathological characteristics in TNBC patients presenting at Chughtai Lab, Lahore. Study Design: Cross Sectional Analytical study. Setting: Chughtai Lab, Lahore. Period: Sep 2024 to Feb 2025. Methods: Newly diagnosed TNBC patients. Based on diagnosis, 85 patients were diagnosed with TNBC. All of the tumors were classified as invasive ductal carcinomas. Immunohistochemistry was performed via DAKO 22C3 pharm-Dx assays. PD-L1 expression was divided into three categories: CPS 0, CPS <10, and CPS ≥10. The date regarding pathological characteristics and demography like patient age, tumor grade, and Ki-67 index was collected. The SPSS version 20 was used for data analysis. Results: Out of 85 TNBC patients, 75 (88.2%) were classified as tumors with grade 3, with 10 (11.8%) classified as grade 2. Regarding the distribution of PD-L1 expression, we found that 7 (8.2%) patients had CPS 0, 20 (23.5%) had CPS <10, and 58 (68.2%) had CPS ≥10. Ki-67 values were greater than 14% for all tumours. PD-L1-positive expression (CPS ≥10) was observed more frequently in grade 3 tumors, and the association was statistically significant (p < 0.001). Conclusion: The study demonstrates the high prevalence of PD-L1 positivity in TNBC patients, indicating that there may be a valuable role for immunotherapy for TNBC patients. This study contributes to the growing body of evidence for the use of PD-L1 testing in the routine diagnostic process for TNBC patients in Pakistan.