By incubating PD-L1-overexpressing PDOs with the PD-1 inhibitor nivolumab, they found that nivolumab induced increased CD8+ T-cell infiltration, decreased PD-L1 expression, and reduced tumor cell proliferation, but its therapeutic effects were concentration-dependent, leading to the hypothesis that nivolumab could be used as a PD-1-targeting agent. This evidence concerns the gene PDCD1 and neoplasm.