title: Improved speciation characteristics of PEGylated indocyanine green-labeled Panitumumab: revisiting the solution and spectroscopic properties of a near-infrared emitting anti-HER1 antibody for optical imaging of cancer.
abstract: A water-soluble amine-reactive PEGylated analogue of near-infrared emitting dye indocyanine green (5) was synthesized and used to label the anti-HER1 antibody panitumumab (Vectibix) at various equivalents. These conjugates were compared with non-PEGylated analogue conjugate products and the solution speciation analyzed with UV-vis spectrophotometry, size exclusion HPLC, and SDS-PAGE. PEGylation of the bioconjugates was successful in preventing aggregation in solution, a phenomenon observed with the non-PEGylated bioconjugates presumably due to the hydrophobicity of indocyanine green. Competitive radioimmunoassay demonstrated that the targeting moiety of the PEGylated bioconjugates was conserved. Fluorescence microscopy also demonstrated membrane binding of the bioconjugate to HER1-expressing A431 cells. Hence, these bioconjugates are suitable candidates for the in vivo optical imaging of HER1-expressing tumors.
authors.affiliation: Radioimmune and Inorganic Chemistry Section, Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-1002, USA.
authors.forename: Aaron Joseph L
authors.initials: AJ
authors.lastname: Villaraza
authors.forename: Diane E
authors.initials: DE
authors.lastname: Milenic
authors.forename: Martin W
authors.initials: MW
authors.lastname: Brechbiel
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000378:metabolism; D001667:Binding, Competitive; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000473:pathology; D045744:Cell Line, Tumor; D002850:Chromatography, Gel; D003952:Diagnostic Imaging / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D018796:Immunoconjugates / Q000737:chemistry / Q000378:metabolism; D007208:Indocyanine Green / Q000031:analogs & derivatives / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D000077544:Panitumumab; D011092:Polyethylene Glycols / Q000737:chemistry; D011863:Radioimmunoassay; D012995:Solubility; D012996:Solutions; D019265:Spectroscopy, Near-Infrared; D014846:Vulvar Neoplasms / Q000175:diagnosis / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D005456:Fluorescent Dyes; D018796:Immunoconjugates; D012996:Solutions; D011092:Polyethylene Glycols; D000077544:Panitumumab; D066246:ErbB Receptors; D007208:Indocyanine Green