PDCD1 and cancer: As the predominant modality of cancer immunotherapy, immunomodulatory monoclonal antibodies (mAbs), including mAbs targeting co-inhibitory or co-stimulatory ligands/receptors of T cells and NK cells (e.g., PDL1, PD1, CTLA4, OX40, 4-1BB, NKG2D, TIGIT)3,40, mAbs re-educating or depleting TAMs (e.g., CSF1R, CCR2)7, and mAbs promoting the phagocytosis of macrophages and dendritic cells (CD47, SIRPα)41,42, may revolutionize the cancer treatment paradigm in the future.