Microsatellite instability (MSI) and Tumor mutation burden (TMB) were considered to be important biomarkers in predicting the response to ICIs, which are represented by anti–programmed death-1/ligand-1 (PD-1/PD-L1) and anti–cytotoxic T lymphocyte antigen-4 (CTLA-4) inhibitors. The gene discussed is PDCD1; the disease is neoplasm.