Significant Association of PD-L1 With CD44 Expression and Patient Survival: Avenues for Immunotherapy and Cancer Stem Cells Downregulation in Pancreatic Cancers.

Background: Pancreatic cancers are known for their aggressive nature. This aggressiveness may be attributed to the presence of cancer stem cells (CSCs), which promote relapse, metastasis, and resistance to chemotherapy. Targeting CSCs is essential to reverse this aggressiveness in pancreatic malignancies. Literature highlights the association of PD-L1 expression with CSCs in various cancers, suggesting immunotherapy as a promising therapeutic approach. This study is aimed at investigating the potential of immunotherapy in pancreatic cancers by examining its association with selected CSC marker expression. Method: A retrospective cohort study was conducted involving 56 patients with confirmed diagnoses of pancreatic cancers at Aga Khan University Hospital from January 2015 to October 2022. After exclusions, based on refusal to provide consent or incomplete follow-up data, 38 patients were enrolled in the study. Immunohistochemistry was performed on formalin-fixed paraffin-embedded (FFPE) tumor tissue samples to assess the expression of CSC markers (CD133, CD44, and L1CAM) and immune checkpoint inhibitor marker (PD-L1). Statistical analysis was employed to determine associations between marker expression, clinical factors, and overall survival. Results: The study revealed that 86.8% of pancreatic cancer cases exhibited positive PD-L1 expression. Moreover, a significant association of PD-L1 expression was observed with the presence of CD44 protein (p = 0.030), as well as with the overall survival of patients (p = 0.023). Conclusion: Our findings show a significant association of PD-L1 with CD44 marker expression as well as patient survival. This research shows the potential to serve as the foundation for investigating the efficacy of immunotherapy in reducing CD44-expressing CSCs in pancreatic cancer, potentially enhancing patient outcomes.