Patients with metastatic, KRAS-mutated lung cancer, treated with at least one cycle of a PD-1 inhibitor or an anti-PD-1/PDL-1 and anti-CTLA-4 combination regimen, had STK11/LKB1 mutations largely drive the primary resistance to PD-1 blockade, in any regimen (Skoulidis et al., 2018). This evidence concerns the gene CTLA4 and lung cancer.