Anti-tumor treatment is divided into drug therapy, radiation therapy, surgical treatment and so on, among which drug therapy includes immunotherapy, chemotherapy, targeted therapy, etc. Among them, anti-tumor immunotherapy, such as targeting PD-1 (programmed death-1 protein-1 (PD-1) or its ligand PD-L1 or CTLA4, aims to strengthen the immune system and exerts anti-tumor effects. The gene discussed is CTLA4; the disease is neoplasm.