Panel Disdussion

3rd International Congress 3rd International of Nuclear Congress Medicine of Nuclear & 15th Medicine Iranian Annual & 15th Iranian Congress Annual of
Nuclear Congress Medicine of Nuclear Medicine
Shahid Beheshti Shahid Beheshti University University of Medical Sciences of Medical 19-21 Sciences May 201119-21 May 2011
A new bombesin kit labeled with 99mTc for breast cancer
imaging
Mostafa Erfani (Gandomkar), Seyed Pejman Shirmardi
Nuclear Science Research School
Introduction: Tumors such as prostate, small cell lung
cancer,breast, gastric and colon cancer are known to over express
receptors to bombesin (BBN). In this study, a new bombesin
analogue was labeled with 99mTc via HYNIC and tricine/EDDA as
coligands and investigated further.
Methods: HYNIC-GABA-Bombesin (7-14) NH2 was synthesized using
a standard Fmoc strategy. Labeling with 99mTc was performed at
100 C for 10 min and radiochemical analysis involved ITLC and HPLC
methods. The stability of radiopeptide was checked in the presence of
humane serum at 37C up to 24 h. The receptor bound internalization
and externalization rates were studied in GRP receptor expressing
PC-3 cells. Biodistribution of radiopeptide was studied in mice.
Results: Labeling yield of 98% was obtained corresponding to a
specific activity of 2.6 MBq/nmol. Peptide conjugate showed good
stability in the presence of human serum. The radioligand showed
high and specific internalization into PC-3 cells (14.63±0.41% at 4
h). In biodistribution studies, a receptor-specific uptake was observed
in GRP-receptor-positive organs so that after 4 h the uptakes in
mouse pancreas was 1.2±0.13% ID/g.
Conclusion: The prepared conjugate showed high accumulation in
pancreas as a positive GRP receptor targeted tissue followed by
excretion via the kidney. These promising characteristics make our
new designed labeled peptide conjugate as a very suitable candidate
for diagnostic of malignant tumors.
Keywords: Radiolabeling, Bombesin, 99mTc, Tumor
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