PDCD1 and lung cancer: Although the novel therapeutic strategies such as targeting drugs toward the epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), and immune checkpoints programmed cell death-1 (PD-1) and/or programmed cell death-1 ligand (PD-L1) have led to an great progress of advanced NSCLC patients among the past decades, the long-term survival of lung cancer remains unfavorable because of the late diagnosis and the frequent resistance to therapeutics (Chansky et al., 2017; Kris et al., 2017).