Engineered modular recombinant transporters: application of new platform for targeted radiotherapeutic agents to alpha-particle emitting 211 At.

Journal Article (Journal Article)

PURPOSE: To generate and evaluate a modular recombinant transporter (MRT) for targeting 211 At to cancer cells overexpressing the epidermal growth factor receptor (EGFR). METHODS AND MATERIALS: The MRT was produced with four functional modules: (1) human epidermal growth factor as the internalizable ligand, (2) the optimized nuclear localization sequence of simian vacuolating virus 40 (SV40) large T-antigen, (3) a translocation domain of diphtheria toxin as an endosomolytic module, and (4) the Escherichia coli hemoglobin-like protein (HMP) as a carrier module. MRT was labeled using N-succinimidyl 3-[211 At]astato-5-guanidinomethylbenzoate (SAGMB), its 125 I analogue SGMIB, or with 131 I using Iodogen. Binding, internalization, and clonogenic assays were performed with EGFR-expressing A431, D247 MG, and U87MG.wtEGFR human cancer cell lines. RESULTS: The affinity of SGMIB-MRT binding to A431 cells, determined by Scatchard analysis, was 22 nM, comparable to that measured before labeling. The binding of SGMIB-MRT and its internalization by A431 cancer cells was 96% and 99% EGFR specific, respectively. Paired label assays demonstrated that compared with Iodogen-labeled MRT, SGMIB-MRT and SAGMB-MRT exhibited more than threefold greater peak levels and durations of intracellular retention of activity. SAGMB-MRT was 10-20 times more cytotoxic than [211 At]astatide for all three cell lines. CONCLUSION: The results of this study have demonstrated the initial proof of principle for the MRT approach for designing targeted alpha-particle emitting radiotherapeutic agents. The high cytotoxicity of SAGMB-MRT for cancer cells overexpressing EGFR suggests that this 211 At-labeled conjugate has promise for the treatment of malignancies, such as glioma, which overexpress this receptor.

Full Text

Duke Authors

Cited Authors

  • Rosenkranz, AA; Vaidyanathan, G; Pozzi, OR; Lunin, VG; Zalutsky, MR; Sobolev, AS

Published Date

  • September 1, 2008

Published In

Volume / Issue

  • 72 / 1

Start / End Page

  • 193 - 200

PubMed ID

  • 18722270

Pubmed Central ID

  • PMC2834178

International Standard Serial Number (ISSN)

  • 0360-3016

Digital Object Identifier (DOI)

  • 10.1016/j.ijrobp.2008.05.055


  • eng

Conference Location

  • United States