ASO Author Reflections: Clinical Significance of PD-L1 Expression in Both Cancer and Stroma Cells in Cholangiocarcinoma Patients

Excerpt

Programmed death-1 (PD-1) and its ligand (PD-L1) showed promising results as therapeutic targets in various hematologic and solid cancers, in both basic and clinical studies1,2. In clinical trials of PD-1/PD-L1 antibodies, an objective response or prolonged disease stabilization were demonstrated in patients with various types of malignancies3. In contrast, strong expression of the PD-L1 ligand on the surface of cancer cells is associated with poor clinical outcomes in various malignancies. Recently, it was appreciated that PD-L1 expression on stroma cells affects the immunosuppressive tumor microenvironment.4 Several reports have shown that such stroma cells overexpress PD-L1 themselves, suppressing cytotoxic T lymphocyte function against tumor cells.5 However, the clinical impact of PD-L1 expression in stroma cells, the relationship between PD-L1 expression in tumor and stroma cells, and how PD-L1 expression affect the immune cell infiltration remain unclear. …