Design and modification of EGF4KDEL 7Mut, a novel bispecific ligand-directed toxin, with decreased immunogenicity and potent anti-mesothelioma activity

Br J Cancer. 2009 Oct 6;101(7):1114-23. doi: 10.1038/sj.bjc.6605297.


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.

Conclusion: 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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • ADP Ribose Transferases / therapeutic use*
  • Animals
  • Bacterial Toxins / therapeutic use*
  • Cell Line, Tumor
  • Epidermal Growth Factor / therapeutic use*
  • Exotoxins / therapeutic use*
  • Female
  • Humans
  • Immunotoxins / immunology
  • Immunotoxins / therapeutic use*
  • Interleukin-4 / therapeutic use*
  • Male
  • Mesothelioma / drug therapy*
  • Mice
  • Mice, Inbred BALB C
  • Peritoneal Neoplasms / drug therapy
  • Recombinant Proteins / therapeutic use
  • Virulence Factors / therapeutic use*
  • Xenograft Model Antitumor Assays


  • Bacterial Toxins
  • Exotoxins
  • Immunotoxins
  • Recombinant Proteins
  • Virulence Factors
  • Interleukin-4
  • Epidermal Growth Factor
  • ADP Ribose Transferases
  • toxA protein, Pseudomonas aeruginosa