CEACAM5

Class

CEACAM5-directed antibody-drug conjugate (precemtabart tocentecan)

Pathway

antibody binds CEACAM5, overexpressed on multiple epithelial solid tumors, delivering a cytotoxic topoisomerase-inhibitor payload upon internalization

CEACAM5 (carcinoembryonic antigen-related cell adhesion molecule 5) is a glycoprotein displayed on the surface of epithelial cells. In several solid tumors—including cancers arising in the lung, colon, and stomach—it is expressed at markedly higher levels than in most normal tissue, making it a useful marker for distinguishing malignant cells. This mechanism exploits that difference through an antibody-drug conjugate (ADC), a molecule that couples a targeting antibody to a cytotoxic chemical payload. The antibody component recognizes and binds CEACAM5 on the tumor cell surface; the complex is then drawn inside the cell (internalized), where the linker connecting antibody to payload is broken down, releasing a topoisomerase inhibitor. Topoisomerase inhibitors block an enzyme required for DNA to unwind during cell division, causing DNA damage that triggers cell death. By concentrating this cytotoxic action specifically in cells expressing high CEACAM5, the approach aims to achieve tumor cell killing while limiting exposure of healthy tissue relative to conventional chemotherapy administered systemically. This general strategy is broadly relevant across epithelial cancers where CEACAM5 overexpression is common, and reflects a wider pharmacological principle: using surface markers as delivery addresses for potent cytotoxic agents that would be too toxic if given unconjugated.