Generally, immune checkpoint blockades, containing programmed cell death receptor 1 (PD-1) and programmed cell death ligand 1 (PD-L1), have received clinical approval for the treatment of a wide variety of cancers such as melanoma, non-small-cell lung carcinoma (NSCLC), microsatellite instability-high (MSI-H), and mismatch repair deficiency (MMR-d) cancers [40]. The gene discussed is PDCD1; the disease is melanoma.