Preliminary studies of EDDA-tricine-HYNIC-[Tyr3]octreotide labelled with Technetium-99m: radiopharmaceutical development for the diagnostic of neuroendocrine tumours

The use of labelled molecules with high specificity for an organ or receptor in scintigraphy, generate good local images of these specific receptors that are expressed for the biomolecule in question, minimizing the exposition of other organs. Small labelled peptides have showed a big potential for tumors image and other diseases in nuclear medicine. The octreotide was the first somatostatin synthetic analog introduced in clinical use in the localization of tumours with superexpression of somatostatin receptors which is a hundred times over in tumors cells that in normal cells. It did many attempts to development of a somatostatin analog labelled with 99mTc utilizing a variety of chelant systems until development the HYNIC-D-Phe1-Tyr3-octreotide, using tricine and EDDA as coligands, showing maintenance of in vivo affinity and promising of biodistribution in animals with induced tumours. This work involved the development of a 99mTc (technetium-99m) radiopharmaceutical based in a somatostatin peptide derivative (Tyr3-octreotide, TOC), with HYNIC chelating group, to be applied in the diagnostic of neuroendocrine tumors in nuclear medicine. Quality control methodologies to be applied in determination of the radiochemical purity of the labelled compound was also studied as well the biodistribution in normal Swiss mouse. The 99mTc-HYNIC-TOC was obtained in high radiochemical yield. Biodistribution studies suggests the potential of this radiopharmaceutical in the diagnostic of neuroendocrine tumours. (author)