Development and characterization of a ^99mTc‐labeled Neuropeptide Y short analog with potential application in breast cancer imaging

Abstract

The aim of this work was to develop and evaluate a 99m Tc-labeled neuropeptide Y derivative with affinity toward Y1-receptor. The selected amino acid sequence included nine amino acids derived from the C-terminal portion of the NPY complemented with the addition of one cysteine-mercaptoacetic acid moiety to bind the radiometal. Labeling was achieved through the preparation of a 3 + 1 nitrido complex. Physicochemical evaluation, cell uptake, internalization and externalization studies, and competitive assays were performed. Biodistribution experiments were carried out in normal and tumor-bearing mice. A single product with radiochemical purity >90% and high stability was obtained. In vitro analysis showed specific cellular uptake, IC 50 of 73.2 nM, and a high internalization rate (80%). Biodistribution studies showed low blood and renal uptake and combined hepatobiliary and urinary elimination. Preliminary studies in mice bearing induced breast tumors rendered promising uptake values. K E Y W O R D Sbreast cancer, neuropeptide Y, radiolabeling, scintigraphy, technetium

Development and characterization of two novel 68Ga‐labelled neuropeptide Y short analogues with potential application in breast cancer imaging

“…No statistically significant difference was observed between them ( p > .05). These values are in the same range of the obtained for the 99m Tc‐NPY analogue previously reported by our group, (IC 50 = 73.2 ± 17.1 nM) (Cardoso et al., 2019). This result confirms that the biological activity of the complexes depends mainly on the peptide sequence and is less dependent on the radionuclide or the chelating agent.…”

“…Our group developed a 99m Tc‐NPY analogue labelled through formation of a ‘3 + 1’ Tc(V)nitrido complex by combining the peptide with a monodentate π‐acceptor phosphine, bound to the [Tc Ξ N] 2+ core. A complex with high radiochemical purity (RCP), good physicochemical properties and promising in vivo and in vitro biological results was obtained (Cardoso et al., 2019).…”

Identification of a Suitable Peptidic Molecular Platform for the Development of NPY(Y1)R‐Specific Imaging Agents

“…Among the studied highly promising truncated NPY analogues, [Lys(lauroyl) 27 ,Pro 30 ,Lys(DOTA) 31 ,Bip 32 ,Leu 34 ]NPY 27-36 ([ 68 Ga]3) not only shows excellent in vitro receptor binding properties (NPY(Y 1 )R affinity and receptor agonism), but -in contrast to the other agents investigated -also a very high stability towards proteolytic degradation by peptidases in human serum and the human liver. It therefore represents the most promising lead compound for the further development of NPY(Y 1 )R-specific molecular imaging agents.…”

“…Over the last two decades, nearly 80 truncated peptides analogues of NPY were developed, exhibiting a linear, cyclic or dimeric peptide backbone in order to identify derivatives with high NPY(Y 1 )R targeting ability. [12,14,15,17,18,19,20,21,29,30] Among these, several showed low affinities, NPY(Y 1 ) receptor subtype selectivities or stabilities. Of those remaining, we chose to directly compare five different peptide analogues regarding their metabolic stability (Figure 1), representing the most promising agents in terms of in vitro properties (NPY(Y 1 )R affinity, Table 1, and receptor subtype selectivity) within their respective group of linear, cyclic and dimeric truncated NPY analogues: i) linear [Pro 30 ,Lys(DOTA) 31 DOTA = (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid), serving as reference compound with known low metabolic stability but high NPY(Y 1 )R affinity and receptor subtype selectivity, [18] ii) [Pro 30 ,Lys(DOTA) 31 ,Bip 32 ,Leu 34 ]NPY [28][29][30][31][32][33][34][35][36] (2), a variant of 1 comprising an artificial Bip (biphenylalanine) amino acid in position 32 instead of tyrosine, [12] and Lys(DOTA) in position 31 for radiolabeling, [15] iii) [Lys(lauroyl) 27 ,Pro 30 ,Lys (DOTA) 31 ,Bip 32 ,Leu 34 ]NPY [27][28][29][30][31][32][33][34]…”

“…Hence, the vast majority of approaches aimed at the development of truncated versions of NPY, ideally showing a strong receptor subtype preference as well as a high affinity to the NPY(Y 1 )R. One challenge is that the peptidereceptor interaction was demonstrated to be highly sensitive to structural changes of the peptide. The C-terminal part of the peptide, NPY [28][29][30][31][32][33][34][35][36] , is the minimal core sequence for receptor binding and Arg33, Arg35 as well as the terminal Tyr36-amide are essential for NPY(Y 1 )R binding. [2,7,8] Furthermore, Thr32 and Gln34 were found to be crucial for receptor subtype preference.…”