title: A deimmunized bispecific ligand-directed toxin that shows an impressive anti-pancreatic cancer effect in a systemic nude mouse orthotopic model.
abstract: OBJECTIVE
  The objective was to test a bispecific ligand-directed toxin (BLT), with reduced immunogenicity for enhanced efficacy in targeting orthotopic pancreatic cancer in vivo.
  
  
  METHODS
  A new BLT was created in which both human epidermal growth factor (EGF) and interleukin 4 cytokines were cloned onto the same single chain molecule with deimmunized pseudomonas exotoxin (dEGF4KDEL). Key amino acids dictating B-cell generation of neutralizing antitoxin antibodies were mutated. Bioassays were used to determine whether mutation reduced potency, and enzyme-linked immunosorbent assay studies were performed to determine whether antitoxin antibodies were reduced. A genetically altered luciferase MIA PaCa-2 xenograft model was used to image in real time and determine effects on systemic malignant human cancer. Bispecific ligand-directed toxins targeting B cells were used as specificity controls.
  
  
  RESULTS
  Deimmunized EGF4KDEL was significantly effective after systemic injection against established orthotopic MIA PaCa-2 pancreatic cancer and selectively prevented metastasis. Mutagenesis significantly reduced antitoxin levels in vivo with no apparent activity loss in vitro. The drug was effective against 3 human pancreatic cancer lines in vitro, MIA PaCa-2, SW1990, and S2VP10.
  
  
  CONCLUSIONS
  Despite the metastatic nature of the MIA PaCa-2 orthotopic tumor xenografted in nude mice, high percentages of tumors responded to extended dEGFKDEL treatment resulting in significant anticancer effects and disease-free survivors.
authors.affiliation: Department of Therapeutic Radiology, University of Minnesota Cancer Center, Minneapolis, MN 55455, USA.
authors.forename: Seunguk
authors.initials: S
authors.lastname: Oh
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Todhunter
authors.forename: Angela
authors.initials: A
authors.lastname: Panoskaltsis-Mortari
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Buchsbaum
authors.forename: Shoko
authors.initials: S
authors.lastname: Toma
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Vallera
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018033:Antibodies, Bispecific / Q000276:immunology / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000276:immunology / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004815:Epidermal Growth Factor / Q000235:genetics / Q000276:immunology; D005098:Exotoxins / Q000235:genetics / Q000276:immunology; D006801:Humans; D000922:Immunotoxins / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D015847:Interleukin-4 / Q000235:genetics / Q000276:immunology; D008024:Ligands; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D011549:Pseudomonas / Q000235:genetics / Q000276:immunology; D013997:Time Factors; D047368:Tumor Burden / Q000187:drug effects / Q000276:immunology; D023041:Xenograft Model Antitumor Assays
chemical_list: D018033:Antibodies, Bispecific; D000970:Antineoplastic Agents; D005098:Exotoxins; D000922:Immunotoxins; D008024:Ligands; D015847:Interleukin-4; D004815:Epidermal Growth Factor