CD68 and neoplasm: In order to examine potential correlations between PD-L1 expression, its spatial distribution and TME alterations during PDAC progression, we performed IHC stainings to detect PD-L1 expression in relation to tumor cells (pan-CK), macrophages (CD68) with an M2-like phenotype (CD163) and CD8+ T cells (CD8) in serial sections from primary tumor (Figure 1A) and corresponding liver metastases (Figure 1B) of four PDAC patients.