The cyclic pentapeptide cyclo(-Arg-Gly-Asp-d-Phe-Lys-) is a highly potent and selective inhibitor for the αvβ3 integrin receptor. A related compound, cyclo(-Arg-Gly-Asp-d-Phe-Val), is a promising anti-cancer drug candidate; it inhibits angiogenesis and induces apoptosis in vascular cells.
Cyclic RGD-containing peptides are selective antagonists of integrins, proteins that play important roles in cell-cell and cell-matrix interactions. In a suitably labelled form, these peptides may serve as useful tools for diagnostic imaging and peptide targeted therapy of some types of cancer.