Summary

Although advances seemed elusive throughout past years, immunotherapy is beginning to fulfill its promise in the treatment of non—small cell lung cancer (NSCLC). For years, researchers have been intrigued by the notion of trying to enlist the immune system to attack tumors; however, little was actually realized until the mechanisms of immune evasion used by tumor cells were defined and immune regulators of the programmed death and programmed death ligand (PD-1—PD-L1) pathway were recently devised. This article discusses the advent of immunotherapy that was made possible by the development of immune checkpoint inhibitors that target the PD-1—PD-L1 pathway.