An anti-CD30 single-chain Fv selected by phage display and fused to Pseudomonas exotoxin A (Ki-4(scFv)-ETA') is a potent immunotoxin against a Hodgkin-derived cell line

Br J Cancer. 1999 Jun;80(8):1214-22. doi: 10.1038/sj.bjc.6690488.


The human CD30 receptor is highly overexpressed on the surface of Hodgkin Reed-Sternberg cells and has been shown to be an excellent target for selective immunotherapy using monoclonal antibody-based agents such as immunotoxins. To construct a new recombinant immunotoxin for possible clinical use in patients with Hodgkin's lymphoma, we have chosen the murine anti-CD30 hybridoma Ki-4 to generate a high-affinity Ki-4 single-chain variable fragment (scFv). Hybridoma V-genes were polymerase chain reaction-amplified, assembled, cloned and expressed as a mini-library for display on filamentous phage. Functional Ki-4 scFv were obtained by selection of binding phage on the Hodgkin lymphoma-derived, CD30-expressing cell line L540Cy. The selected recombinant Ki-4 scFv was shown to specifically bind to an overlapping epitope on the CD30 antigen with binding kinetics similar to those of the original antibody. The Ki-4 scFv was subsequently fused to a deletion mutant of Pseudomonas exotoxin A (ETA'). The resulting immunotoxin Ki-4(scFv)-ETA' specifically binds to CD30+ L540Cy cells and inhibits the protein synthesis by 50% at a concentration (IC50) of 43 pM. This recombinant immunotoxin is a promising candidate for further clinical evaluation in patients with Hodgkin's lymphoma or other CD30+ malignancies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Toxins / pharmacology*
  • Exotoxins / genetics
  • Exotoxins / pharmacology
  • Hodgkin Disease / immunology*
  • Hodgkin Disease / pathology
  • Humans
  • Hybridomas
  • Immunotoxins / pharmacology*
  • Ki-1 Antigen / immunology*
  • Ki-1 Antigen / therapeutic use
  • Peptide Fragments
  • Pseudomonas
  • Recombinant Fusion Proteins / genetics*
  • Reed-Sternberg Cells / drug effects
  • Reed-Sternberg Cells / immunology*
  • Tumor Cells, Cultured


  • Bacterial Toxins
  • Exotoxins
  • Immunotoxins
  • Ki-1 Antigen
  • Peptide Fragments
  • Recombinant Fusion Proteins