ICI targeting the programmed death receptor (ligand) 1 (PD-1/PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) axis are widely applied in solid malignancies such as melanoma, lung cancer, renal cell carcinoma, head and neck squamous cell carcinoma, among others. The gene discussed is CTLA4; the disease is lung cancer.