Synthesis of a Covalent Epirubicin-(C3-amide)-Anti-HER2/neu Immunochemotherapeutic Utilizing a UV-Photoactivated Anthracycline Intermediate

Abstract The C3-monoamine on the carbohydrate moiety (daunosamine -NH2-3′) of epirubicin was reacted under anhydrous conditions with succinimidyl 4,4-azipentanoate to create a covalent UV-photoactivated epirubicin-(C3-amide) intermediate with primary amine-reactive properties. A synthetic covalent bond between the UV-photoactivated epirubicin-(C3-amide) intermediate and the ɛ-amine of lysine residues within the amino acid sequence of anti-HER2/neu monoclonal immunoglobulin was subsequently created by exposure to UV light (354 nm) for 15 minutes. Size-separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis combined with immunodetection analysis and chemiluminescent autoradiographic imaging revealed a lack of IgG-IgG polymerization or degradative protein fragmentation of the covalent epirubicin-(C3-amide)-[anti-HER2/neu] immunochemotherapeutic. Retained binding-avidity of epirubicin-(C3-amide)-[anti-HER2/neu] was validated by cell-ELISA utilizing monolayer populations of chemotherapeutic-res...