Panel Disdussion

3rd International Congress of of Nuclear Medicine & & 15th 15th Iranian Annual Annual Congress of
Congress of Nuclear Medicine
Shahid Beheshti Shahid Beheshti University University of Medical of Medical Sciences Sciences 19-21 19-21 May May 2011
Synthesis and evaluation of [99mTc-HYNIC]-BOC-ATE as a
new somatostatin analogue for receptor scintigraphy
Mostafa Erfani(Gandomkar), Reza Najafi
Nuclear Science Research School
Introduction: Radiolabeled somatostatin analogues have been
successfully used for targeted radiotherapy and imaging of
somatostatin receptor (sstr) positive tumours. In an effort to make
available radiolabeled analogues with a broader spectrum and able to
target other sstr in addition to sstr2, [DOTA0, 1-Nal3]-octreotate has
been recently developed. In this study the preclinical evaluation of
Boc-Octreotate labeled with 99mTc using HYNIC chelator and
ethylenediamine-N,N'-diacetic acid (EDDA) as a coligands is
described.
Methods: Peptide was synthesized on a solid phase following typical
Fmoc/Boc protection strategies. Labeling with 99mTc was performed
at 100 °C for 10 min using SnCl2 as reducing agent. Radiochemical
analysis involved ITLC and HPLC methods. The internalization rate
was studied in sstr2 expressing AR4-2J. Biodistribution was studied in
rats.
Results: [99mTc-EDDA-HYNIC]-Boc-ATE was prepared in high
radiochemical yield and purity (>95%). The radiopeptide showed a
fast and specific internalization into AR4-2J cells (15.17% ± 0.81% at
4 h). In animal biodistribution studies a receptor-specific uptake of
radioactivity was observed in sstr-positive organs like pancrase (1.83
± 0.33 %ID/g).
Conclusions: These data show that radioligand have a potential to
target tumours with sstr2 and sstr3 expression, either alone or
concomitantly with other subtypes. [99mTc-EDDA-HYNIC]-Boc-ATE
might prove to be useful in the diagnostic imaging of tumours
expressing sstr2 or additional receptor subtypes.
Keywords: Somatostatin, 99mTc, Tumour
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