PDCD1 and lung cancer: Recent research has fostered new insights into lung cancer biology, and considerable progress has been made in the field of novel biomarker‐targeted therapies, including molecular therapies targeting epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK) and proto‐oncogene B‐Raf (BRAF), 2, 3 and immunotherapies with checkpoint inhibitors targeting the programmed cell death 1 (PD‐1) and programmed death‐ligand 1 (PD‐L1) pathways.4