title: Development of multivalent radioimmunonanoparticles for cancer imaging and therapy.
abstract: BACKGROUND
  Noninvasive, focused hyperthermia can be achieved by using an externally applied alternating magnetic field (AMF) if effective concentrations of nanoparticles can be delivered to the target cancer cells. Targeting agents, for example, monoclonal antibodies or peptides, linked to magnetic iron oxide nanoparticles (NP), represent a promising strategy to target cancer cells and hyperthermia.
  
  
  METHODS
  We have developed a new radioconjugate NP ((111)In-DOTA-di-scFv-NP), using recombinantly generated antibody fragments, di-scFv-c, for the imaging and therapy of anti-MUC-1-expressing cancers, because aberrant MUC-1 is abundantly expressed on the majority of human epithelial cancers. Anti-MUC-1 di-scFv-c (50 kDa) were engineered, generated, and selected to link maleimide functionalized nanoparticles (NP-M). DOTA chelate was conjugated with di-scFv-c for radionuclide chelation to trace the radioimmunonanoparticles (RINPs) in vivo.
  
  
  RESULTS
  Heat-inducing NP-M were prepared with maleimide density >15 per particle for site-specific thiolation. The specific activity of the RINP was 4-5 microCi (111)In/mg with >10 molecules of di-scFv per NP. We characterized the RINP by polyacrylamide gel electrophoresis, cellulose acetate electrophoresis, size-exclusion chromatography, and tumor-cell binding. RINP had a >90% di-scFv conjugated to NP and an immunoreactivity >80% relative to unmodified di-scFv-c on HBT 3477 and DU145 tumor cells. Pharmacokinetics and whole-body autoradiography studies demonstrated that a 5% injected dose was targeted in tumor after 24 hours.
  
  
  CONCLUSIONS
  Further development of this new preparation of RINP may provide uniquely high tumor-targeting NP for AMF-driven tumor hyperthermia with less spleen and kidney accumulation.
authors.affiliation: Department of Internal Medicine, University of California Davis, Sacramento, California, USA. arutselvan.natarajan@ucdmc.ucdavis.edu
authors.forename: Arutselvan
authors.initials: A
authors.lastname: Natarajan
authors.forename: Cheng-Yi
authors.initials: CY
authors.lastname: Xiong
authors.forename: Cordula
authors.initials: C
authors.lastname: Gruettner
authors.forename: Gerald L
authors.initials: GL
authors.lastname: DeNardo
authors.forename: Sally J
authors.initials: SJ
authors.lastname: DeNardo
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D015153:Blotting, Western; D019556:COS Cells; D002522:Chlorocebus aethiops; D005260:Female; D005290:Ferric Compounds / Q000737:chemistry / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000276:immunology; D007205:Indium Radioisotopes / Q000493:pharmacokinetics / Q000627:therapeutic use; D008280:Magnetics; D008301:Maleimides / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D018396:Mucin-1 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D053758:Nanoparticles / Q000627:therapeutic use*; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000276:immunology / Q000532:radiotherapy*; D011859:Radiography; D016719:Radioimmunodetection; D016499:Radioimmunotherapy; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D005290:Ferric Compounds; D007135:Immunoglobulin Variable Region; D007205:Indium Radioisotopes; D008301:Maleimides; D018396:Mucin-1; C000499:ferric oxide; C043592:maleimide