PDCD1 and pancreatic neoplasm: The low amount of infiltrating PD-1 expressing immune cells in PDAC tissues was recently confirmed by conventional immunohistochemistry.9 Moreover, CD8+ and CD4+ T cells co-expressing CD39 and CD103 were only observed in one patient that showed a higher mutational load than the remaining samples, suggesting an absence of tumor-reactive T cells in the majority of pancreatic tumors.