PDCD1 and non-small cell lung carcinoma: So far the US Food and Drug Administration (FDA) has approved only two IgG4-κ monoclonal antibodies (mAbs) for PD-1 inhibition, pembrolizumab (humanised; Keytruda®, Merck) and nivolumab (fully human; Opdivo®, Bristol-Myers Squibb), for the treatment of patients with unresectable or metastatic melanoma and metastatic squamous non-small-cell lung cancer (NSCLC)8.