CD274 and breast cancer: The genomic subtypes of breast cancer in this study were characterized by diverse tumor ecosystems where basal-like tumors, which consisted mostly of TNBC, showed 3 different phenotypes with one enriched for hormone receptor negative cells and high Ki67; another phenotype enriched for epithelial cells expressing basal cytokeratins; and a phenotype associated with hypoxia which had CD274 copy number gain and B2M loss that could be linked to immune resistance [107].