Increased antitumor activity of a circularly permuted interleukin 4-toxin in mice with interleukin 4 receptor-bearing human carcinoma

Cancer Res. 1995 Aug 1;55(15):3357-63.


We reported previously that circularly permuted interleukin-4 (IL4), composed of amino acids 38-129 of IL4 connected by a linker peptide GGNGG to amino acids 1-37, is preferable to native IL4 for fusing to the amino terminus of truncated Pseudomonas exotoxin (PE) to make a recombinant toxin, because the new ligand-toxin junction results in improved IL4 receptor (IL4R)-binding (R. J. Kreitman et al., Proc. Natl. Acad. Sci. USA, 91: 6889-6893, 1994). We now report that the improved binding of circularly permuted IL4-toxin is associated with improved antitumor activity in tumor-bearing mice. For in vivo testing, we made an improved circularly permuted IL4-toxin, termed IL4(38-37)-PE38KDEL. It contains an N38D mutation at the amino terminus, allowing improved expression and large-scale production in Escherichia coli. It also contains the truncated toxin PE38KDEL, which is composed of amino acids 253-364 and 381-608 of PE, followed by KDEL. To evaluate antitumor activity, nude mice carrying s.c. tumors composed of IL4R-bearing human A431 epidermoid carcinoma cells were injected with recombinant toxins i.v. every other day for three doses. IL4(38-37)-PE38KDEL induced complete remissions in 80% of mice receiving 50 micrograms/kg x 3 and 100% of mice receiving 100 micrograms/kg x 3, while only 70% of mice receiving 200 micrograms/kg x 3 of the native IL4-toxin IL4-PE38KDEL obtained complete remission. Disease-free survival after obtaining complete remissions was higher in mice treated with IL4(38-37)-PE38KDEL 50 micrograms/Kg QOD x 3 than with IL4-PE38KDEL 200 micrograms/Kg QOD x 3 (P < 0.03). IL4(38-37)-PE38KDEL and IL4-PE38KDEL exhibited similar toxicity and pharmacokinetics in the mice, indicating that the improved antitumor activity of the circularly permuted IL4-toxin was due to its improved binding to the IL4R on the target cells.

MeSH terms

  • ADP Ribose Transferases*
  • Animals
  • Bacterial Toxins / chemistry
  • Bacterial Toxins / pharmacokinetics
  • Bacterial Toxins / therapeutic use*
  • Carcinoma / drug therapy*
  • Carcinoma / metabolism
  • Cells, Cultured
  • Drug Screening Assays, Antitumor
  • Escherichia coli / drug effects
  • Exotoxins / chemistry
  • Exotoxins / pharmacokinetics
  • Exotoxins / therapeutic use*
  • Female
  • Humans
  • Immunotoxins / chemistry
  • Immunotoxins / pharmacokinetics
  • Immunotoxins / therapeutic use*
  • Interleukin-4 / chemistry
  • Interleukin-4 / pharmacokinetics
  • Interleukin-4 / therapeutic use*
  • Mice
  • Mice, Nude
  • Peptide Fragments / chemistry
  • Peptide Fragments / pharmacokinetics
  • Peptide Fragments / therapeutic use
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / pharmacokinetics
  • Recombinant Fusion Proteins / therapeutic use*
  • Virulence Factors*


  • Bacterial Toxins
  • Exotoxins
  • Immunotoxins
  • Peptide Fragments
  • Recombinant Fusion Proteins
  • Virulence Factors
  • Interleukin-4
  • ADP Ribose Transferases
  • toxA protein, Pseudomonas aeruginosa