PDCD1 and thoracic cancer: Monoclonal antibodies directed against cytotoxic T lymphocyte antigen 4 (CTLA4) or programmed cell death 1 (PD-1) or its cognate ligand PD-L1 have received regulatory approval across the globe, alone or in combination with chemotherapy, for the treatment of a variety of malignancies, including other thoracic cancers such as NSCLC and SCLC [22,23,24,25].