Immune checkpoint inhibitors showed a strong antitumor effect (ORR: 39.8%; 95% CI 34.9–44.8) in TMB-H tumors for cancer types in which tissue invasive CD8 T-cell levels showed a positive correlation with neoantigen levels, such as malignant melanoma, lung cancer, and bladder cancer. The gene discussed is CD8A; the disease is urinary bladder carcinoma.