PDCD1 and neoplasm: Penpulimab is a humanized monoclonal antibody against immunoglobulin G1 (IgG1), which binds to programmed cell death protein 1 (PD-1) receptors to block their interaction with programmed death-ligand (PD-L)1 and PD-L2, thereby blocking the immunosuppressive response mediated by the PD-1 pathway, including the anti-tumor immune response (1).