EGFR and lung cancer: In most patients with lung cancer and non-T790 M-mediated epidermal growth factor receptor (EGFR) mutations, the downstream JAK/STAT, AKT/mTOR, and mitogen-activated protein kinase (MAPK)1 pathways are not activated, resulting in unexpressed PD-L1 and resistance to PD-1 blockade therapy [129–135].