Discloses use of an effective amount of an R-G-Cysteic Acid Peptide, or a functional derivative thereof selected from the group consisting of a pharmaceutically acceptable salt, hydrate, stereoisomer, multimer, cyclic form, linear form and drug-conjugate, in the manufacture of a medicament for inhibiting adhesion to RGD binding sites in a human or animal subject, provided that the R-G-Cysteic Acid Peptide is not Glycine- Arginine-Glycine-Cysteic(Acid)-Threonine-Proline.