Based on our findings reported here, if a checkpoint blockade therapy only inhibits the PD-L1/PD-1 signaling pathway and leaves the PD-L1/CD80 signaling pathway intact, then PD-L1 expressed by tumor cells will still be able to induce apoptosis of tumor-infiltrating CD8+ T cells by signaling through CD80. This evidence concerns the gene CD80 and neoplasm.