The use of immune checkpoint inhibitors (ICIs)—monoclonal antibodies targeting programmed death protein 1 (PD-1), programmed death protein 1 ligand (PD-L1) and CTLA-4—has yielded impressive results in many settings and is currently a cornerstone in the treatment of metastatic melanoma, non-small-cell lung carcinoma (NSCLC), renal cell carcinoma (RCC), urothelial carcinoma and Hodgkin’s lymphoma (HL) [1,2,3,4,5]. The gene discussed is CTLA4; the disease is non-small cell lung carcinoma.