With the advancement of lung cancer therapy, ICI therapy has become a first-line treatment regimen for non-operative locally advanced and metastatic NSCLC and SCLC, of which PD1 inhibitor (PD-1 antibody and PD-L1 antibody) is the most widely used, followed by CTLA-4 inhibitor [2]. The gene discussed is CTLA4; the disease is small cell lung carcinoma.