PDCD1 and pancreatic neoplasm: Based on the analyses of single cell sequencing technologies, the specific gene expression signatures of cancer-associated fibroblasts (CAF) have been identified to be associated with poor responses to anti-PD1 or anti-PDL1 antibodies in breast cancer and pancreatic cancer, respectively (Dominguez et al., 2020; Kieffer et al., 2020).