Oxidized avidin (AvidinOX) (AvidinOX)

Oxidized avidin (AvidinOX) is a chemically modified form of the chicken egg-white protein avidin, where carbohydrate side chains are oxidized to generate reactive aldehyde groups (De Santis et al., 2005). These aldehydes allow the protein to form stable covalent Schiff base bonds with primary amines on tissue proteins, effectively anchoring it at the site of injection for several weeks (Gallo et al., 2007). Despite this modification, the protein maintains its exceptionally high affinity for biotin, acting as a localized neo-receptor (Paganelli et al., 2010). This system is used in a pre-targeting strategy where AvidinOX is injected into a tumor, followed by the administration of biotinylated therapeutic agents like radionuclides. The high-affinity binding pocket captures these agents, concentrating the treatment at the disease site while reducing systemic exposure. It has been primarily investigated for the treatment of solid tumors, including glioblastoma and liver metastases, to improve the therapeutic index of radiotherapy. However, because avidin is a non-human protein, its use can trigger the production of human anti-avidin antibodies (HAAA), which may limit repeated dosing or cause hypersensitivity.

Other names

OX-AvidinPeriodate-oxidized avidinAldehyde-activated avidinAvidinOX-biotin binding pocket

AvidinOX acts as a stable, tissue-bound receptor that captures biotinylated agents via the high-affinity avidin-biotin interaction after being covalently anchored to the extracellular matrix through Schiff base formation (De Santis et al., 2005; Gallo et al., 2007).