Extra domain B fibronectin (EDB-FN) (EDB-FN)

Extra domain B fibronectin (EDB-FN) is an alternatively spliced isoform of the extracellular matrix glycoprotein fibronectin, characterized by the inclusion of a specific 91-amino acid domain (ED-B) [1, 14]. It is classified as an oncofetal antigen because it is highly expressed during embryonic development and in the stroma and neovasculature of most aggressive solid tumors, but is virtually absent in healthy adult tissues [4, 14]. EDB-FN plays a pivotal role in the tumor microenvironment by promoting angiogenesis, cell migration, and tissue remodeling, primarily through its interaction with integrin receptors such as αvβ3 [7, 18]. Due to its exceptional tumor-to-normal expression ratio and accessibility in the subendothelial extracellular matrix, it serves as a high-quality target for antibody-based cancer therapies [3, 8]. Therapeutic strategies targeting EDB-FN include immunocytokines (e.g., L19-IL2, L19-TNF), radioimmunotherapy (e.g., Radretumab), and antibody-drug conjugates (ADCs) that deliver cytotoxic payloads to the tumor site [11, 14, 17]. Clinical trials have explored these agents across various malignancies, including malignant glioma, melanoma, and lung cancer, often using EDB-specific imaging for patient selection [1, 14].

Other names

ED-BEDBOncofetal fibronectinEDB+FNExtra-domain B of fibronectinB-FN

Drugs targeting EDB-FN typically utilize high-affinity antibodies, such as the L19 clone, to achieve selective accumulation in the tumor microenvironment and neovasculature [4, 14]. These agents function by delivering potent payloads—including proinflammatory cytokines (e.g., IL-2, TNF-alpha), radioisotopes for imaging or radiotherapy, or cytotoxic drugs via antibody-drug conjugates (ADCs)—directly to the tumor site [3, 14]. Because EDB-FN is a non-internalizing extracellular matrix protein, ADCs targeting it often rely on the extracellular release of the payload and subsequent bystander killing of adjacent tumor cells [3, 12].