Construction of anti-EGFR immunoliposomes via folate–folate binding protein affinity

• Published in: International journal of pharmaceutics 2007-05, Vol.336 (2), p.276-283
• Main Authors: Pan, Xiaogang, Lee, Robert J.
• Format: Article
• Language: English
• Subjects: Antibodies, Monoclonal - administration & dosage; Antibodies, Monoclonal - pharmacology; Antibodies, Monoclonal, Humanized; Antineoplastic Agents - administration & dosage; Antineoplastic Agents - pharmacology; Biological and medical sciences; Biological Transport; Carrier Proteins - administration & dosage; Carrier Proteins - pharmacology; Cell Line, Tumor; Cetuximab; Doxorubicin - administration & dosage; Doxorubicin - pharmacology; Drug Delivery Systems; Drug Stability; Drug targeting; EGF receptor; Flow Cytometry; Folate; Folate binding protein; Folate Receptors, GPI-Anchored; Folic Acid; General pharmacology; Glioblastoma; Humans; Hydrogen-Ion Concentration; Immunoconjugates - administration & dosage; Immunoconjugates - pharmacology; Immunoliposomes; Liposomes; Medical sciences; Microscopy, Fluorescence; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Polycarboxylate Cement; Receptor, Epidermal Growth Factor - drug effects; Receptor, Epidermal Growth Factor - immunology; Receptor, Epidermal Growth Factor - metabolism; Receptors, Cell Surface - administration & dosage
• ISSN: 0378-5173; 1873-3476
• DOI: 10.1016/j.ijpharm.2006.12.007

A novel method for synthesis of anti-EGFR immunoliposomes using folate–folate binding protein (FBP) affinity is described. An anti-EGFR antibody (cetuximab or C225) was covalently linked to FBP via a thioether bond. Liposomes incorporating a lipophilic folate derivative (folate-PEG-cholesterol) were prepared by polycarbonate membrane extrusion. Anti-EGFR immunoliposomes were then obtained by combining FBP-C225 and folate-liposomes and evaluated for uptake and cytotoxicity in EGFR-overexpressing U87 human glioblastoma cells. Anti-EGFR immunoliposomes constructed via folate–FBP affinity exhibited excellent stability under physiological pH, and quickly released the bound FBP-C225 upon low pH (pH 3.5) treatment. Flow cytometry and fluorescence microscopy showed similar receptor-specific binding and internalization for both folate–FBP affinity-coupled and covalently coupled C225-immunoliposomes, but not for the non-targeted IgG-immunoliposomes. C225-immunoliposomes loaded with anticancer drug doxorubicin were more cytotoxic than non-targeted immunoliposomes in EGFR-overexpressing U87 glioma cells. Folate–FBP affinity is a potential method for construction of immunoliposomes and may have applications in synthesis of targeted drug carriers in general.