title: Anticalins directed against the fibronectin extra domain B as diagnostic tracers for glioblastomas.
abstract: The standard of care for diagnosis and therapy monitoring of gliomas is magnetic resonance imaging (MRI), which however, provides only an indirect and incomplete representation of the tumor mass, offers limited information for patient stratification according to WHO-grades and may insufficiently indicate tumor relapse after antiangiogenic therapy. Anticalins are alternative binding proteins obtained via combinatorial protein design from the human lipocalin scaffold that offer novel diagnostic reagents for histology and imaging applications. Here, the Anticalins N7A, N7E and N9B, which possess exquisite specificity and affinity for oncofetal fibronectin carrying the extra domain B (ED-B), a well-known proangiogenic extracellular matrix protein, were applied for immunohistochemical studies. When investigating ED-B expression in biopsies from 41 patients with confirmed gliomas of WHO grades I to IV, or in non-neoplastic brain samples, we found that Anticalins specifically detect ED-B in primary glioblastoma multiforme (GBM; WHO IV) but not in tumors of lower histopathological grade or in tumor-free brain. In primary GBM samples, ED-B specific Anticalins locate to fibronectin-rich perivascular areas that are associated with angiogenesis. Anticalins specifically detect ED-B both in fixed tumor specimen and on vital cells, as evidenced by cytofluorometry. Beyond that, we labeled an Anticalin with the γ-emitter (123) I and demonstrated specific binding to GBM-tissue samples using in vitro autoradiography. Overall, our data indicate that ED-B specific Anticalins are useful tools for the diagnosis of primary GBM and related angiogenic sites, presenting them as promising tracers for molecular tumor imaging.
authors.affiliation: Department of Neurosurgery, Neurosurgical Research, University of Munich, Munich, Germany.
authors.forename: Valerie
authors.initials: V
authors.lastname: Albrecht
authors.affiliation: Munich Center for Integrated Protein Science (CIPS-M) & Lehrstuhl für Biologische Chemie, Technische Universität München, Freising-Weihenstephan, Germany.
authors.forename: Antonia
authors.initials: A
authors.lastname: Richter
authors.affiliation: Department of Nuclear Medicine, University of Munich, Munich, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Pfeiffer
authors.affiliation: Munich Center for Integrated Protein Science (CIPS-M) & Lehrstuhl für Biologische Chemie, Technische Universität München, Freising-Weihenstephan, Germany.
authors.forename: Michaela
authors.initials: M
authors.lastname: Gebauer
authors.affiliation: Department of Nuclear Medicine, University of Munich, Munich, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Lindner
authors.affiliation: Department of Neurosurgery, Neurosurgical Research, University of Munich, Munich, Germany.
authors.forename: Eugenie
authors.initials: E
authors.lastname: Gieser
authors.affiliation: Center for Neuropathology and Prion Research, University of Munich, Munich, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schüller
authors.affiliation: Department of Neurosurgery, Neurosurgical Research, University of Munich, Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Schichor
authors.affiliation: Department of Nuclear Medicine, University of Munich, Munich, Germany.
authors.forename: Franz Josef
authors.initials: FJ
authors.lastname: Gildehaus
authors.affiliation: Department of Nuclear Medicine, University of Munich, Munich, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Bartenstein
authors.affiliation: Department of Neurosurgery, Neurosurgical Research, University of Munich, Munich, Germany.
authors.forename: Jörg-Christian
authors.initials: JC
authors.lastname: Tonn
authors.affiliation: Munich Center for Integrated Protein Science (CIPS-M) & Lehrstuhl für Biologische Chemie, Technische Universität München, Freising-Weihenstephan, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Skerra
authors.affiliation: Department of Neurosurgery, Neurosurgical Research, University of Munich, Munich, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Glass
mesh_terms: D000906:Antibodies / Q000378:metabolism*; D001932:Brain Neoplasms / Q000737:chemistry / Q000175:diagnosis*; D045744:Cell Line, Tumor; D005353:Fibronectins / Q000032:analysis* / Q000378:metabolism; D005909:Glioblastoma / Q000737:chemistry / Q000175:diagnosis*; D006801:Humans; D007150:Immunohistochemistry; D054834:Lipocalins / Q000276:immunology* / Q000378:metabolism; D057054:Molecular Imaging / Q000379:methods*; D019151:Peptide Library; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D011485:Protein Binding; D017434:Protein Structure, Tertiary
chemical_list: D000906:Antibodies; D005353:Fibronectins; D054834:Lipocalins; D019151:Peptide Library; D019408:Platelet Endothelial Cell Adhesion Molecule-1; C121542:oncofetal fibronectin
keywords: brain tumor diagnosis; immunohistochemistry; lipocalin; molecular imaging tracer; oncofetal fibronectin; protein engineering; protein scaffold