Optimised labeling, preclinical and initial clinical aspects of CCK-2 receptor-targeting with 3 radiolabeled peptides.

Medullary thyroid carcinoma (MTC) expresses CCK-2 receptors. (111)In-labeled DOTA-DGlu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH(2) (DOTA-MG11), DOTA-DAsp-Tyr-Nle-Gly-Trp-Nle-Asp-Phe-NH(2) (DOTA-CCK), and (99m)Tc-labeled N(4)-Gly-DGlu-(Glu)(5)-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH(2) ((99m)Tc-Demogastrin 2) are analogs developed for CCK-2 receptor-targeted scintigraphy. All 3 radiolabeled analogs were selected on the basis of their high CCK-2 receptor affinity and their good in vitro serum stability, with in vitro serum t(1/2) values of several hours.

Comparison of [(177)Lu-DOTA(0),Tyr(3)]octreotate and [(177)Lu-DOTA(0),Tyr(3)]octreotide: which peptide is preferable for PRRT?

Purpose: Patients with somatostatin receptor subtype 2-positive metastasised neuroendocrine tumours can be treated with [(177)Lu-DOTA(0),Tyr(3)]octreotate. Some use octreotide as the peptide for peptide receptor radionuclide therapy (PRRT). We compared in seven patients [(177)Lu-DOTA(0),Tyr(3)]octreotide ((177)Lu-DOTATOC) and [(177)Lu-DOTA(0),Tyr(3)]octreotate ((177)Lu-DOTATATE), to see which peptide should be preferred for PRRT with (177)Lu.

[(99m)Tc]Demotate 2 in the detection of sst(2)-positive tumours: a preclinical comparison with [(111)In]DOTA-tate.

Purpose: The aim of this study was to evaluate [(99m)Tc]Demotate 2 ([(99m)Tc-N(4) (0-1),Asp(0),Tyr(3)]octreotate) as a candidate for in vivo imaging of sst(2)-positive tumours and to compare it with [(111)In]DOTA-tate ([(111)In-DOTA(0),Tyr(3)]octreotate).

Methods: Labelling of Demotate 2 with (99m)Tc was performed at room temperature using SnCl(2) as reductant in the presence of citrate at alkaline pH. Radiochemical analysis involved ITLC and HPLC methods.

Inhomogeneous localization of radioactivity in the human kidney after injection of [(111)In-DTPA]octreotide.

Unlabelled: In peptide receptor radionuclide therapy (PRRT) using somatostatin analogs labeled with beta-emitters, the radiosensitive kidney is the dose-limiting organ, because of high uptake and retention of the radionuclides after glomerular filtration. Dosimetry calculations are mostly based on the MIRD scheme, assuming homogeneous renal radioactivity distribution. The aim of this study was to reveal the radioactivity distribution in the normal human kidney after intravenous injection of [(111)In-diethylenetriaminepentaacetic acid (DTPA)]octreotide.

Radiolabeled RGD-DTPA-Tyr3-octreotate for receptor-targeted radionuclide therapy.

The aim of this study was to develop and investigate a radiopeptide for the treatment of cancers which overexpress cell surface somatostatin receptors. The new radiopharmaceutical is composed of a somatostatin receptor-targeting peptide, a chelator (DTPA) to enable radiolabeling, and an apoptosis-inducing RGD (arginine-glycine-aspartate) peptide moiety. The receptor-targeting peptide portion of the molecule, Tyr3-octreotate, is specific for the somatostatin subtype-2 cell surface receptor (sst2), which is overexpressed on many tumor cells.