title: Design and modification of EGF4KDEL 7Mut, a novel bispecific ligand-directed toxin, with decreased immunogenicity and potent anti-mesothelioma activity.
abstract: BACKGROUND
  Potency, immunogenicity, and toxicity are three problems that limit the use of targeted toxins in solid tumour therapy.
  
  
  METHODS
  To address potency, we used genetic engineering to develop a novel bispecific ligand-directed toxin (BLT) called EGF4KDEL, a novel recombinant anti-mesothelioma agent created by linking human epidermal growth factor (EGF) and interleukin-4 (IL-4) to truncated pseudomonas exotoxin (PE38) on the same single-chain molecule. Immunogenicity was reduced by mutating seven immunodominant B-cell epitopes on the PE38 molecule to create a new agent, EGF4KDEL 7Mut.
  
  
  RESULTS
  In vitro, bispecific EGF4KDEL showed superior anti-mesothelioma activity compared with its monospecific counterparts. Toxicity in mice was diminished by having both ligands on the same molecule, allowing administration of a 10-fold greater dose of BLT than a mixture of monomeric IL4KDEL and EGFKDEL. EGF4KDEL 7Mut, retained all of its functional activity and induced about 87% fewer anti-toxin antibodies than mice given the parental, non-mutated form. In vivo, intraperitoneal (IP) injection of the BLT showed significant (P<0.01) and impressive effects against two aggressive, malignant IP mesothelioma models when treatment was begun 14-16 days post tumour innoculation.
  
  
  CONCLUSIONS
  These data show that EGF4KDEL 7Mut is a promising new anti-mesothelioma agent that was developed to specifically address the obstacles facing clinical utility of targeted toxins.
authors.affiliation: Department of Therapeutic Radiology-Radiation Oncology, Section on Molecular Cancer Therapeutics, Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Stish
authors.forename: S
authors.initials: S
authors.lastname: Oh
authors.forename: H
authors.initials: H
authors.lastname: Chen
authors.forename: A Z
authors.initials: AZ
authors.lastname: Dudek
authors.forename: R A
authors.initials: RA
authors.lastname: Kratzke
authors.forename: D A
authors.initials: DA
authors.lastname: Vallera
mesh_terms: D036002:ADP Ribose Transferases / Q000627:therapeutic use*; D000818:Animals; D001427:Bacterial Toxins / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D004815:Epidermal Growth Factor / Q000627:therapeutic use*; D005098:Exotoxins / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D000922:Immunotoxins / Q000276:immunology / Q000627:therapeutic use*; D015847:Interleukin-4 / Q000627:therapeutic use*; D008297:Male; D008654:Mesothelioma / Q000188:drug therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D010534:Peritoneal Neoplasms / Q000188:drug therapy; D011994:Recombinant Proteins / Q000627:therapeutic use; D037521:Virulence Factors / Q000627:therapeutic use*; D023041:Xenograft Model Antitumor Assays; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D001427:Bacterial Toxins; D004815:Epidermal Growth Factor; D005098:Exotoxins; D000922:Immunotoxins; D015847:Interleukin-4; D011994:Recombinant Proteins; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A