CD276 (B7-H3) is a type I transmembrane protein and immune checkpoint inhibitor that is induced on antigen presenting cells. It plays a role in the inhibition of T-cell function. It is expressed constitutively on fibroblasts, endothelial cells, and osteoblasts. It is also induced on immune cells, particularly antigen-presenting dendritic cells, monocytes, NK cells, B cells, and some T-cells. It is overexpressed in a range of human cancers, including melanomas, leukemia, breast, prostate, ovarian, pancreatic, and colorectal cancers, while limited expression is seen in normal tissues. Overexpression of CD276 correlates with poor prognosis, suggesting that CD276 plays a role in immune evasion and tumorigenesis. It is a target for cancer immunotherapy and a candidate for inhibitory immune checkpoint blockade.