For metastatic non-small cell lung cancer (NSCLC), the introduction of immune checkpoint inhibitors (ICIs) targeting programmed death-1 (PD-1), programmed death ligand 1 (PD-L1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) has markedly improved survival rates in both first-line and second-line treatments over the past decade (9). Here, CTLA4 is linked to small cell lung carcinoma.