Dataset Information

Toward Stability Enhancement of NTS₁R-Targeted Radioligands: Structural Interventions on [^99mTc]Tc-DT1.

ABSTRACT: The neurotensin subtype 1 receptor (NTS₁R) is overexpressed in a number of human tumors, thereby representing a valid target for cancer theranostics with radiolabeled neurotensin (NT) analogs like [^99mTc]Tc-DT1 (DT1, N₄-Gly⁷-NT(8-13)). Thus far, the fast degradation of intravenously injected NT-radioligands by neprilysin (NEP) and angiotensin-converting enzyme (ACE) has compromised their clinical applicability. Aiming at metabolic stability enhancements, we herein introduce (i) DT7 ([DAsn¹⁴]DT1) and (ii) DT8 ([β-Homoleucine¹³]DT1), modified at the C-terminus, along with (iii) DT9 ([(palmitoyl)Lys⁷]DT1), carrying an albumin-binding domain (ABD) at Lys⁷. The biological profiles of the new [^99mTc]Tc-radioligands were compared with [^99mTc]Tc-DT1, using NTS₁R-expressing AsPC-1 cells and mice models without or during NEP/ACE inhibition. The radioligands showed enhanced in vivo stability vs. [^99mTc]Tc-DT1, with [^99mTc]Tc-DT9 displaying full resistance to both peptidases. Furthermore, [^99mTc]Tc-DT9 achieved the highest cell internalization and tumor uptake even without NEP/ACE-inhibition but with unfavorably high background radioactivity levels. Hence, unlike C-terminal modification, the introduction of a pendant ABD group in the linker turned out to be the most promising strategy toward metabolic stability, cell uptake, and tumor accumulation of [^99mTc]Tc-DT1 mimics. To improve the observed suboptimal pharmacokinetics of [^99mTc]Tc-DT9, the replacement of palmitoyl on Lys⁷ by other ABD groups is currently being pursued.

SUBMITTER: Kanellopoulos P

PROVIDER: S-EPMC10459693 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature

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Toward Stability Enhancement of NTS1R-Targeted Radioligands: Structural Interventions on [99mTc]Tc-DT1.

Kanellopoulos Panagiotis P Nock Berthold A BA Krenning Eric P EP Maina Theodosia T

Pharmaceutics 20230807 8

The neurotensin subtype 1 receptor (NTS1R) is overexpressed in a number of human tumors, thereby representing a valid target for cancer theranostics with radiolabeled neurotensin (NT) analogs like [99mTc]Tc-DT1 (DT1, N4-Gly7-NT(8-13)). Thus far, the fast degradation of intravenously injected NT-radioligands by neprilysin (NEP) and angiotensin-converting enzyme (ACE) has compromised their clinical applicability. Aiming at metabolic stability enhancement ...[more]

PMID: 37631306

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Project description:This study sought to evaluate [(99m)Tc(HYNIC-Galacto-RGD2)(tricine)(TPPTS)] ((99m)Tc-Galacto-RGD2: HYNIC = 6-hydrazinonicotinyl; Galacto-RGD2 = Glu[cyclo[Arg-Gly-Asp-D-Phe-Lys(SAA-PEG2-(1,2,3-triazole)-1-yl-4-methylamide)]]2 (SAA = 7-amino-L-glycero-L-galacto-2,6-anhydro-7-deoxyheptanamide, and PEG2 = 3,6-dioxaoctanoic acid); and TPPTS = trisodium triphenylphosphine-3,3',3″-trisulfonate) as a new radiotracer for tumor imaging. Galacto-RGD2 was prepared via the copper(I)-catalyzed 1,3-dipolar azide-alkyne Huisgen cycloaddition. HYNIC-Galacto-RGD2 was prepared by reacting Galacto-RGD2 with sodium succinimidyl 6-(2-(2-sulfonatobenzaldehyde)hydrazono)nicotinate (HYNIC-OSu) in the presence of diisopropylethylamine, and was evaluated for its integrin αvβ3 binding affinity against (125)I-echistatin bound to U87MG glioma cells. The IC50 value for HYNIC-Galacto-RGD2 was determined to be 20 ± 2 nM. (99m)Tc-Galacto-RGD2 was prepared in high specific activity (∼ 185 GBq/μmol) and high radiochemical purity (>95%), and was evaluated in athymic nude mice bearing U87MG glioma xenografts for its tumor-targeting capability and biodistribution. The tumor uptake of (99m)Tc-Galacto-RGD2 was 10.30 ± 1.67, 8.37 ± 2.13, 6.86 ± 1.33, and 5.61 ± 1.52%ID/g at 5, 30, 60, and 120 min p.i., respectively, which was in agreement with high integrin αvβ3 expression on glioma cells and neovasculature. Its lower uptake in intestines, lungs, and spleen suggests that (99m)Tc-Galacto-RGD2 has advantages over (99m)Tc-3P-RGD2 ([(99m)Tc(HYNIC-3P-RGD2)(tricine)(TPPTS)]: 3P-RGD2 = PEG4-E[PEG4-c(RGDfK)]2; PEG4 = 15-amino-4,7,10,13-tetraoxapentadecanoic acid) for imaging tumors in the chest and abdominal regions. U87MG tumors were readily detected by SPECT and the tumor uptake of (99m)Tc-Galacto-RGD2 was integrin αvβ3-specific. (99m)Tc-Galacto-RGD2 also had very high metabolic stability. On the basis of results from this study, it was concluded that (99m)Tc-Galacto-RGD2 is an excellent radiotracer for imaging integrin αvβ3-positive tumors and related metastases.

Dataset Information

Toward Stability Enhancement of NTS₁R-Targeted Radioligands: Structural Interventions on [^99mTc]Tc-DT1.

Publications

Toward Stability Enhancement of NTS<sub>1</sub>R-Targeted Radioligands: Structural Interventions on [<sup>99m</sup>Tc]Tc-DT1.

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