CEACAM-5
CEACAM-5, historically known as carcinoembryonic antigen (CEA), is a cell surface glycoprotein of the carcinoembryonic antigen-related cell adhesion molecule family, with an N-terminal IgV-like domain followed by six IgC2-like domains attached to the membrane by a GPI anchor. Expressed transiently in fetal gut and at low levels in adult gastrointestinal mucosa, CEACAM5 is strongly re-expressed in colorectal, gastric, and pancreatic adenocarcinomas. Serum CEACAM5 remains a mainstay tumor marker for colorectal cancer surveillance, and its surface density on tumor cells supports CEACAM5-directed bispecific antibodies and CAR-T therapies in clinical development. Its glycosylated ectodomain is shed into serum, forming the basis of clinical CEA assays.
