title: Bispecific Her2 × cotinine antibody in combination with cotinine-(histidine)2-iodine for the pre-targeting of Her2-positive breast cancer xenografts.
abstract: OBJECTIVE
  Cotinine has optimal characteristics as a hapten for pre-targeted radioimmunotherapy (PRIT). This study was performed to evaluate the applicability of cotinine/anti-cotinine antibody to PRIT.
  
  
  METHODS
  We developed and prepared a tandem, single-chain, variable fragment Fc fusion protein [tandem single-chain variable fragment (scFv) Fc fusion protein] that is reactive to both human epidermal growth factor receptor 2 (Her2) and cotinine. Its simultaneous reactivity to Her2 and cotinine was tested in an enzyme-linked immunosorbent assay (ELISA) and two radioimmunoassays (RIA) employing Her2-coated RIA tubes and a Her2-overexpressing cell line. For in vivo imaging, mice bearing Her2-positive tumors were injected with a mixture of tandem scFv Fc fusion and (125)I-cotinine-conjugated histidine dipeptide ((125)I-cotinine peptide). After a delay, (125)I-cotinine peptide was injected again.
  
  
  RESULTS
  ELISA and RIA results showed that tandem scFv Fc fusion protein successfully bound to both Her2 and cotinine. In single-photon emission computed tomography (SPECT), the complex of tandem scFv Fc fusion protein and (125)I-cotinine peptide was localized to Her2-positive tumor xenografts in mice 4 h after the first injection. Enhanced radioactivity at the site of the Her2-positive tumor lesion was monitored 1 h after the second injection.
  
  
  CONCLUSIONS
  With these findings, we conclude that the tandem scFv Fc fusion protein and cotinine hapten system have the potential to be applied in PRIT.
authors.affiliation: Department of Biochemistry and Molecular Biology, Seoul National University School of Medicine, Seoul, 110-799, Republic of Korea.
authors.forename: Soomin
authors.initials: S
authors.lastname: Yoon
authors.forename: Yun-Hee
authors.initials: YH
authors.lastname: Kim
authors.forename: Se Hun
authors.initials: SH
authors.lastname: Kang
authors.forename: Seok-Ki
authors.initials: SK
authors.lastname: Kim
authors.forename: Hwa Kyoung
authors.initials: HK
authors.lastname: Lee
authors.forename: Hyori
authors.initials: H
authors.lastname: Kim
authors.forename: Junho
authors.initials: J
authors.lastname: Chung
authors.forename: In-Hoo
authors.initials: IH
authors.lastname: Kim
mesh_terms: D000818:Animals; D018033:Antibodies, Bispecific / Q000276:immunology* / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000276:immunology / Q000378:metabolism / Q000628:therapy*; D003367:Cotinine / Q000737:chemistry / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D064593:Heterografts; D006639:Histidine / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007457:Iodine Radioisotopes; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D011863:Radioimmunoassay; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000276:immunology*; D057127:Single-Chain Antibodies / Q000276:immunology* / Q000627:therapeutic use; D014407:Tumor Cells, Cultured
chemical_list: D018033:Antibodies, Bispecific; D003367:Cotinine; D006639:Histidine; D007457:Iodine Radioisotopes; D018719:Erb-b2 Receptor Tyrosine Kinases; D011993:Recombinant Fusion Proteins; D057127:Single-Chain Antibodies; C508053:ERBB2 protein, human