CD274 and breast cancer: For breast cancer, multiple trials with breast cancer vaccines to deliver shared tumor antigens have demonstrated safe and inducible antigen-specific immune responses.7 Promising effects of immune checkpoint inhibitors have been shown with the potential of harnessing the immune system for clinical benefit.7 Checkpoint inhibitors target cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and the programmed cell death protein-1 (PD-1)/programmed cell death ligand-1 (PD-L1).