It has been shown that immune checkpoints, such as programmed death 1 (PD‐1) or its ligand (PD‐L1) and cytotoxic T‐lymphocyte‐associated protein 4 (CTLA‐4), could expand the application on certain advanced stage of tumors including SCLC (Pakkala & Owonikoko, 2018; Tian et al., 2019). This evidence concerns the gene CTLA4 and small cell lung carcinoma.