Vol 57, No 4 (2006)
Original paper
Published online: 2006-07-07
The use of a new analogue DGlu-Octagastrin in scintigraphy of medullary thyroid carcinoma
Endokrynol Pol 2006;57(4):427-430.
Abstract
Introduction: Medullary thyroid carcinomas (MTC) reveal
overexpression of several peptide receptors particularly of
gastrin and cholecystokinin 2 (CCK2). Experimental studies
of various CCK-2/gastrin analogues found that a C-terminal,
8-aminoacid peptide, DGlu-octagastrin, has optimal properties.
Thus, the aim of our studies was to prepare 99mTc-labelled
HYNIC-octagastrin, to evaluate its biologic tolerance in
animals and introduce for scintigraphy in patients with MTC.
Material and methods: HYNIC-DGlu-octagastrin was from piCHEM (Graz, Austria), 99mTc generator from Amersham (Health), other reagents were purchased from Sigma. Labelling of the peptide was performed in phosphate buffer of pH 6.0 for 10 minutes at 100oC using EDDA and tricine as coligands.
Results: The labeling yields were high (above 95%); the specific activity amounted to 1200 to 1430 μCi/μg. Radiochemical purity on SepPak cartridge and ITLC ranged from 94 to 98%. No adverse effects were observed in mice after administration of 10 to 50 times greater doses that those used in patients. Clinical studies comprised 20 patients with MTC and high serum calcitonin. 99mTc-EDDA/HYNIC-DGlu-octagastrin, 500 to 700 MBq, was administered iv and whole body scintigraphy was performed using a double head gamma-camera (Varicam, Elscint) 2 and 4 hours later. Increased accumulation of the tracer in foci of MTC and its metastases was found in 8 patients.
Conclusions: Scintigraphy with a new gastrin analogue (DGlu-octagastrin) makes it possible to detect MTC with overexpression of CCK-2/gastrin receptors and to select patients for receptor-mediated radiopeptide therapy using DOTA-gastrin analogues labelled with 177Lu and 90Y.
Material and methods: HYNIC-DGlu-octagastrin was from piCHEM (Graz, Austria), 99mTc generator from Amersham (Health), other reagents were purchased from Sigma. Labelling of the peptide was performed in phosphate buffer of pH 6.0 for 10 minutes at 100oC using EDDA and tricine as coligands.
Results: The labeling yields were high (above 95%); the specific activity amounted to 1200 to 1430 μCi/μg. Radiochemical purity on SepPak cartridge and ITLC ranged from 94 to 98%. No adverse effects were observed in mice after administration of 10 to 50 times greater doses that those used in patients. Clinical studies comprised 20 patients with MTC and high serum calcitonin. 99mTc-EDDA/HYNIC-DGlu-octagastrin, 500 to 700 MBq, was administered iv and whole body scintigraphy was performed using a double head gamma-camera (Varicam, Elscint) 2 and 4 hours later. Increased accumulation of the tracer in foci of MTC and its metastases was found in 8 patients.
Conclusions: Scintigraphy with a new gastrin analogue (DGlu-octagastrin) makes it possible to detect MTC with overexpression of CCK-2/gastrin receptors and to select patients for receptor-mediated radiopeptide therapy using DOTA-gastrin analogues labelled with 177Lu and 90Y.
Keywords: medullary carcinomagastrin analoguesradiopeptide scintigraphy99mTc-HYNIC-Octagastrin
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