PDCD1 and neoplasm: Pembrolizumab (MK-3475) is a fully humanized IgG4 monoclonal antibody against PD-1.In a phase Ib trial (Keynote-001 study), pembrolizumab demonstrated promisingclinical efficacy, particularly in patients with high PD-L1 expression.13 A subsequent open-label randomized phase II/III clinical trial (Keynote-10)compared pembrolizumab with docetaxel in patients with metastatic NSCLC whosedisease had progressed on prior chemotherapy and expressed PD-L1 staining of atleast 1% tumor proportion score.