title: Preclinical screening of anti-HER2 nanobodies for molecular imaging of breast cancer.
abstract: Accurate determination of tumor human epidermal growth factor receptor 2 (HER2)-status in breast cancer patients is possible via noninvasive imaging, provided adequate tracers are used. In this study, we describe the generation of a panel of 38 nanobodies, small HER2-binding fragments that are derived from heavy-chain-only antibodies raised in an immunized dromedary. In search of a lead compound, a subset of nanobodies was biochemically characterized in depth and preclinically tested for use as tracers for imaging of xenografted tumors. The selected compound, 2Rs15d, was found to be stable and to interact specifically with HER2 recombinant protein and HER2-expressing cells in ELISA, surface plasmon resonance, flow cytometry, and radioligand binding studies with low nanomolar affinities, and did not compete with anti-HER2 therapeutic antibodies trastuzumab and pertuzumab. Single-photon-emission computed tomography (SPECT) imaging quantification and biodistribution analyses showed that (99m)Tc-labeled 2Rs15d has a high tumor uptake in 2 HER2(+) tumor models, fast blood clearance, low accumulation in nontarget organs except kidneys, and high concomitant tumor-to-blood and tumor-to-muscle ratios at 1 h after intravenous injection. These values were dramatically lower for an irrelevant control (99m)Tc-nanobody and for (99m)Tc-2Rs15d targeting a HER2(-) tumor.
authors.affiliation: In Vivo Cellular and Molecular Imaging Laboratory, Vrije Universiteit Brussel Laarbeeklaan 103, 1090 Brussels, Belgium. ilse.vaneycken@gmail.com
authors.forename: Ilse
authors.initials: I
authors.lastname: Vaneycken
authors.forename: Nick
authors.initials: N
authors.lastname: Devoogdt
authors.forename: Naomi
authors.initials: N
authors.lastname: Van Gassen
authors.forename: Cécile
authors.initials: C
authors.lastname: Vincke
authors.forename: Catarina
authors.initials: C
authors.lastname: Xavier
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wernery
authors.forename: Serge
authors.initials: S
authors.lastname: Muyldermans
authors.forename: Tony
authors.initials: T
authors.lastname: Lahoutte
authors.forename: Vicky
authors.initials: V
authors.lastname: Caveliers
mesh_terms: D000818:Animals; D000918:Antibody Specificity / Q000276:immunology; D001943:Breast Neoplasms / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D016466:CHO Cells; D002161:Camelids, New World; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D006801:Humans; D008325:Mammary Neoplasms, Experimental / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D057054:Molecular Imaging / Q000379:methods*; D019151:Peptide Library; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology*; D057127:Single-Chain Antibodies / Q000235:genetics / Q000276:immunology* / Q000493:pharmacokinetics; D013667:Technetium / Q000493:pharmacokinetics; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon; D014183:Transplantation, Heterologous; D055114:X-Ray Microtomography
chemical_list: D019151:Peptide Library; D018719:Erb-b2 Receptor Tyrosine Kinases; D057127:Single-Chain Antibodies; D013667:Technetium