PDCD1 and neoplasm: This study provides a comprehensive functional characterization of finotonlimab, a humanized anti-PD-1 monoclonal drug of the IgG4 subtype, including in vitro T cell activation effects, in vivo anti-tumor activity in mouse models, Fc-mediated effector functions, and PK, RO, and safety properties of finotonlimab after single or successive doses in cynomolgus monkeys.