[111In]Bz-DTPA-hEGF: Preparation and in vitro characterization of a potential anti-glioblastoma targeting agent

Åsa Liljegren Sundberg, Anna Orlova, Alexander Bruskin, Lars Gedda, Jörgen Carlsson, Erik Blomquist, Hans Lundqvist, Vladimir Tolmachev

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

The overexpression of epidermal growth factor receptors, EGFR, in glioblastomas is well documented. Hence, the EGFR can be used as target structure for a specific targeting of glioblastomas. Both radiolabeled anti-EGFR antibodies and the natural ligand EGF are candidate agents for targeting. However, EGF, which has a rather low molecular weight (6 kDa), might have better tissue penetration properties through both normal tissue and tumors in comparison with anti-EGF antibodies and their fragments. The aim of this study was to prepare and evaluate in vitro an EGF-based antiglioma conjugate with residualizing label. Human recombinant EGF (hEGF) was coupled to isothiocyanate-benzyl-DTPA. The conjugate was purified from unreacted chelator using solid-phase extraction and labeled with 111In. The labeling yield was 87% ± 7%. The label was reasonably stable; the transchelation of 111In to serum proteins was about 5% after incubation at 37°C during 24 hours. The obtained [111In]benzyl-DTPA-hEGF conjugate was characterized in vitro using the EGFR expressing glioma cell line U343MGaCl2:6. The binding affinity, internalization, and retention of the conjugate were studied. The conjugate had receptor specific binding and the radioactivity was quickly internalized. The intracellular retention of radioactivity after interrupted incubation with conjugate was 71% ± 1% and 59% ± 1.5% at 24 and 45 hours, respectively. The dissociation constant was estimated to 2. 0 nM. The results indicate that [111In]benzyl-DTPA-hEGF is a potential candidate for targeting glioblastoma cells, possibly using locoregional injection.

Original languageEnglish
Pages (from-to)643-654
Number of pages12
JournalCancer Biotherapy and Radiopharmaceuticals
Volume18
Issue number4
DOIs
Publication statusPublished - 2003
Externally publishedYes

Keywords

  • Chelators
  • EGF
  • Glioblastomas
  • Radiometals
  • Tumor targeting

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Pharmacology
  • Cancer Research

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