Anti-Human CEACAM5 Monoclonal Antibody (Labetuzumab)

CEACAM5 (Carcinoembryonic Antigen-Related Cell Adhesion Molecule 5), better known as carcinoembryonic antigen (CEA), is an acidic glycoprotein first discovered in colorectal cancer and named accordingly. It belongs to the immunoglobulin superfamily. Under normal circumstances, its expression level in the colonic epithelium of adults is extremely low, but it becomes significantly overexpressed in a variety of epithelial tumors, particularly colorectal cancer, gastric cancer, pancreatic cancer, lung cancer, and breast cancer. Through its extracellular adhesion domain, this protein mediates homophilic or heterophilic intercellular interactions. Its core function is a "double-edged sword": under normal physiological conditions, it acts as an adhesion molecule involved in maintaining tissue structural integrity; however, within the tumor microenvironment, highly expressed CEACAM5 delivers inhibitory signals into cells via its intracellular immunoreceptor tyrosine-based inhibitory motif (ITIM), thereby suppressing the activity of immune cells (such as T cells and NK cells) and facilitating tumor immune evasion. Based on these properties, CEACAM5 is not only the most widely used tumor serum biomarker in clinical practice (for monitoring treatment efficacy and follow-up for recurrence), but has also emerged in recent years as a highly promising therapeutic target.