Until recently, the prognosis and treatment of patients with advanced-stage 
squamous cell lung cancers have been limited. An improvement in the 
understanding of the role of the immune system in tumor immunosurveillance has 
led to the development of the programmed death-1 (PD-1) immune checkpoint 
inhibitor nivolumab (Opdivo). Nivolumab is the first PD-1 inhibitor approved for 
the treatment of advanced-stage squamous cell non-small-cell lung cancer 
following platinum-based chemotherapy. In the key Phase III trial CHECKMATE 017, 
a better overall survival and progression-free survival were seen in patients 
treated with second-line nivolumab compared with docetaxel. Programmed death 
ligand-1 (PD-L1) expression did not predict for outcome. In addition, nivolumab 
had better safety and tolerability, and led to better patient reported outcomes. 
Further research on the role of PD-L1 expression as a predictive biomarker 
should be performed, and other biomarkers that can predict the efficacy of 
PD-1/PD-L1 inhibitors should also be pursued. Further studies on the combination 
treatment are ongoing to determine the optimal role of nivolumab as monotherapy 
or nivolumab with other agents in non-small-cell lung cancer.