PDCD1 and neoplasm: In the study, we presented new evidence that PD-L1 expression suppresses tumor-killing activity of CIK cells against allogeneic tumor cell lines, and PD-L1/PD-1 blockade strengthens tumoricidal activity of CIK cells, providing preclinical data for simultaneous PD-L1/PD-1 blockade along with CIK infusion as a novel treatment approach for gastrointestinal cancer patients.