title: DOTAGA-trastuzumab. A new antibody conjugate targeting HER2/Neu antigen for diagnostic purposes.
abstract: Improved bifunctional chelating agents (BFC) are required for indium-111 radiolabeling of monoclonal antibodies (mAbs) under mild conditions to yield stable, target-specific agents. 2,2',2"-(10-(2,6-Dioxotetrahydro-2H-pyran-3-yl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid (DOTAGA-anhydride) was evaluated for mAb conjugation and labeling with indium-111. The DOTA analogue was synthesized and conjugated to trastuzumab-which targets the HER2/neu receptor-in mild conditions (PBS pH 7.4, 25 °C, 30 min) and gave a mean degree of conjugation of 2.6 macrocycle per antibody. Labeling of this immunoconjugate with indium-111 was performed in 75% yield after 1 h at 37 °C, and the proportion of (111)In-DOTAGA-trastuzumab reached 97% after purification. The affinity of DOTAGA-trastuzumab was 5.5 ± 0.6 nM as evaluated by in vitro saturation assays using HCC1954 breast cancer cell line. SPECT/CT imaging and biodistribution studies were performed in mice bearing breast cancer BT-474 xenografts. BT-474 tumors were clearly visualized on SPECT images at 24, 48, and 72 h postinjection. The tumor uptake of [(111)In-DOTAGA]-trastuzumab reached 65%ID/g 72 h postinjection. These results show that the DOTAGA BFC appears to be a valuable tool for biologics conjugation.
authors.affiliation: Institut de Chimie Moléculaire de l'Université de Bourgogne , UMR CNRS 6302, 21078 Dijon Cedex, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Moreau
authors.forename: Olivier
authors.initials: O
authors.lastname: Raguin
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Vrigneaud
authors.forename: Bertrand
authors.initials: B
authors.lastname: Collin
authors.forename: Claire
authors.initials: C
authors.lastname: Bernhard
authors.forename: Xavier
authors.initials: X
authors.lastname: Tizon
authors.forename: Frédéric
authors.initials: F
authors.lastname: Boschetti
authors.forename: Olivier
authors.initials: O
authors.lastname: Duchamp
authors.forename: François
authors.initials: F
authors.lastname: Brunotte
authors.forename: Franck
authors.initials: F
authors.lastname: Denat
mesh_terms: D000812:Anhydrides / Q000737:chemistry; D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000737:chemistry; D001940:Breast / Q000473:pathology; D001943:Breast Neoplasms / Q000175:diagnosis*; D045744:Cell Line, Tumor; D005260:Female; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry; D007205:Indium Radioisotopes / Q000737:chemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis*; D015899:Tomography, Emission-Computed, Single-Photon; D000068878:Trastuzumab
chemical_list: D000812:Anhydrides; D061067:Antibodies, Monoclonal, Humanized; D006573:Heterocyclic Compounds, 1-Ring; D018796:Immunoconjugates; D007205:Indium Radioisotopes; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C574967:DOTAGA-anhydride