PDCD1 and cancer: Overall, tumor immunotherapy strategies, such as cancer vaccines (e.g., cell-based vaccines), ACTs (e.g., CAR-based-ACTs, TCR-based-ACTs), ICIs (e.g., anti-PD-1 ICIs, anti-PD-L1 ICIs), mAbs, and OVs therapy (e.g., Vaccinia virus based OVs) have implemented clinical trials and some have achieved good results.