Blocking the interactions of PD-L1 and PD-1 shuts off the inhibitory signaling pathways for T cells, reactivates the T cell–mediated anti-tumor responses by promoting T-cell proliferation, and enhances effector T-cell function (Salmaninejad et al., 2019; Tang and Zheng., 2018). The gene discussed is PDCD1; the disease is neoplasm.