CTLA4 and cancer: Over the past six years, results of several Phase I to III clinical trials of cancer immunotherapy targeting immune checkpoints (initially CTLA-4 and subsequently the PD-1/PD-L1 axis) have fostered the dawn of a new era in the treatment of several advanced cancers including melanoma, non-small cell lung cancer (NSCLC), urothelial cancer, renal cancer, head and neck squamous cell carcinoma, triple-negative breast cancer, gastric cancer, colorectal cancer, Merkel cell carcinomas, and Hodgkin’s lymphomas.