Pharmacokinetics and stability of the ch14.18-interleukin-2 fusion protein in mice

Cancer Immunol Immunother. 1999 Aug;48(5):219-29. doi: 10.1007/s002620050569.


The fusion protein formed from ch14.18 and interleukin-2 (ch14.18-IL-2), shown to exhibit antitumor efficacy in mouse models, consists of IL-2 genetically linked to each heavy chain of the ch14.18 chimeric anti-GD2 monoclonal antibody. The purpose of this study was to determine the pharmacokinetics of ch14.18-IL-2 in mice and assess its stability in murine serum. Following i.v. injection, the fusion protein was found to have a terminal half-life of 4.1 h. Detection of IL-2 following injection of the ch14.18-IL-2 fusion protein showed a similar half-life, indicating that the fusion protein prolongs the circulatory half-life of IL-2. Detection of human IgG1 following injection of ch14.18-IL-2 showed a terminal half-life of 26.9 h. These data suggested that the native fusion protein is being altered in vivo, resulting in a somewhat rapid loss of detectable IL-2, despite prolonged circulation of its immunoglobulin components. In vitro incubation of the ch14.18-IL-2 fusion protein in pooled mouse serum at 37 degrees C for 48 h resulted in a loss of its IL-2 component, as detected in enzyme-linked immunosorbent assay systems and in proliferation assays. Polyacrylamide gel electrophoresis and Western blot analysis of the fusion protein incubated in mouse serum at 37 degrees C indicated that the ch14.18-IL-2 is cleaved, resulting in a loss of the 67-kDa band (representing the IL-2 linked to the IgG1 heavy chain) and the detection of a band of more than 50 kDa, slightly heavier than the IgG1 heavy chain itself. This suggests that the fusion protein is being cleaved in vitro within the IL-2 portion of the molecule. These studies show that (1) ch14.18-IL-2 prolongs the circulatory half-life of IL-2 (compared to that of soluble IL-2) and (2) the in vivo clearance of the fusion protein occurs more rapidly than the clearance of the ch14.18 antibody itself, possibly reflecting in vivo cleavage within the IL-2 portion of the molecule, resulting in loss of IL-2 activity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / blood
  • Antibodies, Monoclonal / chemistry*
  • Antibodies, Monoclonal / pharmacokinetics
  • Antibodies, Monoclonal / pharmacology*
  • Drug Stability
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Flow Cytometry
  • Humans
  • Immunization, Passive / methods
  • Interleukin-2 / blood
  • Interleukin-2 / chemistry*
  • Interleukin-2 / pharmacokinetics*
  • Mice
  • Mice, Inbred BALB C
  • Recombinant Fusion Proteins / blood
  • Recombinant Fusion Proteins / chemistry*
  • Recombinant Fusion Proteins / pharmacokinetics*
  • Temperature
  • Time Factors


  • Antibodies, Monoclonal
  • Interleukin-2
  • Recombinant Fusion Proteins
  • dinutuximab