Targeting the immune checkpoint pathways of CTLA4, PD-1 and PD-L1 has been remarkably successful in melanoma, non-small cell lung cancer (NSCLC) and urothelial cancers, and is currently being investigated extensively in clinical trials for patients with gastroesophageal cancer [1,2,27,28]. The gene discussed is PDCD1; the disease is non-small cell lung carcinoma.