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Updated: Aug 14, 2026
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Pretargeted Radioimmunotherapy Based on the Inverse Electron Demand Diels-Alder Reaction
Published on: January 29, 2019
Trifunctional somatostatin-based derivatives designed for targeted radiotherapy using auger electron emitters
Mihaela Ginj1, Karin Hinni, Sibylle Tschumi
1Division of Radiological Chemistry, Department of Radiology, University Hospital Basel, Basel, Switzerland.
Summary
New somatostatin conjugates with nuclear localization signals (NLS) enhance Auger electron therapy by increasing cellular retention and nuclear accumulation. This improves targeted radionuclide therapy for small cancers.
Area of Science:
- Nuclear medicine
- Oncology
- Radiopharmaceutical chemistry
Background:
- Auger electron-emitting radionuclides offer potent cancer therapy due to high cytotoxicity and short-range effectiveness.
- Effective radionuclide therapy relies on precise subcellular localization, particularly nuclear targeting.
Purpose of the Study:
- To design, synthesize, and evaluate novel trifunctional somatostatin conjugates for targeted radionuclide therapy.
- To enhance cellular retention and nuclear accumulation of Auger electron emitters for improved cancer treatment.
Main Methods:
- Synthesized three trifunctional somatostatin derivatives (DOTA-TOC) incorporating a nuclear localization signal (NLS).
- Utilized solid and solution phase peptide synthesis for conjugate preparation.
- Labeled compounds with 111In and assessed binding affinity, internalization, and nuclear localization in cancer and embryonic cell lines.
Main Results:
- N-terminal NLS derivatives maintained sstr2A binding affinity and showed superior internalization compared to the parent compound.
- One N-terminal derivative demonstrated a 6-fold increase in cellular retention and a 45-fold higher nuclear accumulation.
- C-terminal conjugates were less effective than the parent compound.
Conclusions:
- Incorporating an NLS sequence into DOTA-TOC enhances its potential as a carrier for Auger electron-emitting radionuclides.
- These findings support the use of NLS-modified conjugates for improved radioactivity retention in tumor cells, advancing targeted radionuclide therapy.
