NCIt definition : A radiotracer composed of a cyclic Arg-Gly-Asp (RGD) peptide that is conjugated with
galactose and radiolabeled with fluorine 18, for potential noninvasive positron emission
tomography (PET) imaging of alphaVbeta3 integrin expression. Upon administration,
the RGD moiety of the fluorine 18 galacto-RGD peptide selectively binds to alphaVbeta3
integrin. During PET imaging, alphaVbeta3-expressing tumor cells can be visualized
and the degree of tumor angiogenesis can be determined. Use of a hydrophilic glycopeptide-based
agent may increase retention in the blood and reduce clearance by the liver. This
leads to both increased uptake of fluorine 18 galacto-RGD peptide by tumor cells and
enhanced PET imaging efficiency, when compared to other agents that are constructed
using lipophilic conjugates. AlphaVbeta3 integrin, a cell adhesion and signaling receptor,
is upregulated in tumor vessel endothelial cells and has been associated with proliferation
of tumor cells, tumor angiogenesis and metastasis.;