FGFR2b

Class

FGFR2b-directed antibody-drug conjugate (topoisomerase I inhibitor payload)

Pathway

FGFR signaling / DNA-damage payload release

FGFR2b is a specific splice variant of fibroblast growth factor receptor 2, a cell-surface receptor tyrosine kinase found on epithelial cells lining organs such as the stomach lining. It normally binds fibroblast growth factors to regulate cell growth, survival, and tissue repair through downstream signaling cascades including RAS-MAPK and PI3K-AKT pathways. In certain cancers, FGFR2b is markedly overexpressed or amplified on tumor cell surfaces, making it a distinguishing marker that can be exploited for targeted drug delivery rather than direct receptor blockade alone. An antibody-drug conjugate directed against FGFR2b uses an antibody to selectively recognize and bind this receptor, then relies on receptor internalization to carry a cytotoxic payload—in this case a topoisomerase I inhibitor—directly into the tumor cell. Once inside, the payload is released and interferes with DNA replication machinery, causing lethal DNA damage. This strategy combines the tumor-selectivity of antibody targeting with the potency of a chemotherapy-class agent, aiming to concentrate cytotoxic effect within FGFR2b-high tumor cells while limiting exposure to normal tissue. This approach is broadly relevant to cancers where FGFR2b overexpression identifies a distinct, targetable tumor population, particularly certain gastrointestinal malignancies.