环己二胺叠氮（CHDT）功能化实现靶标分子与Al18F/68Ga/111In的标记

Cyclohexanediamine Triazole (CHDT) Functionalization Enables Labeling of Target Molecules with Al18F/68Ga/111In

BIOCONJUGATE CHEMISTRY

影响因子:3.9

分区:化学2区 / 生化研究方法2区有机化学2区生化与分子生物学3区化学：综合3区

发表日期:2024 Sep 18

作者: Wiebke Sihver, Martin Walther, Martin Ullrich, Anne-Kathrin Nitt-Weber, Jenny Böhme, Falco Reissig, Magdalena Saager, Kristof Zarschler, Christin Neuber, Jörg Steinbach, Klaus Kopka, Hans-Jürgen Pietzsch, Robert Wodtke, Jens Pietzsch

DOI: 10.1021/acs.bioconjchem.4c00313

摘要

Al18F标记方法通过模拟放射性金属的标记过程，提供了一步法制备放射性氟化的生物分子的方法。尽管这些条件被认为比传统放射性氟化更温和，但螯合单元的改良已催生了(±)-H3RESCA，已能在室温下实现Al18F标记。在蛋白质的功能化和放射性氟化方面，(±)-H3RESCA已被广泛验证，但其在小分子或肽上的应用仍较少。本研究在此基础上，通过引入炔基官能团，发展了一种用于生物大分子后期标记的点击反应策略。结果显示，除了Al18F标记外，环己二胺叠氮（CHDT）基团还可以稳定复合68Ga和111In。合成了三种新型CHDT功能化的前列腺特异性膜抗原（PSMA）抑制剂，并对其Al18F、68Ga和111In标记的类似物进行了详细的体外放射药理学表征。在人体血清中的稳定性研究表明所有放射性金属配合物均具有较高的动力学惰性。此外，Al18F标记的PSMA配体在LNCaP衍生肿瘤异种移植小鼠模型中的体内成像显示，其性能优于[18F]PSMA-1007，且在120分钟后具有更高的肿瘤/血液和肿瘤/肌肉比值。总体而言，研究结果强调了新型CHDT基团在小分子或肽的功能化及Al18F、68Ga、111In的放射性标记中的应用潜力，叙环的药代动力学特性有利于分子影像的应用。

Abstract

The Al18F-labeling approach offers a one-step access to radiofluorinated biomolecules by mimicking the labeling process for radiometals. Although these labeling conditions are considered to be mild compared to classic radiofluorinations, improvements of the chelating units have led to the discovery of (±)-H3RESCA, which allows Al18F-labeling already at ambient temperature. While the suitability of (±)-H3RESCA for functionalization and radiofluorination of proteins is well established, its use for small molecules or peptides is less explored. Herein, we advanced this acyclic pentadentate ligand by introducing an alkyne moiety for the late-stage functionalization of biomolecules via click chemistry. We show that in addition to Al18F-labeling, the cyclohexanediamine triazole (CHDT) moiety allows stable complexation of 68Ga and 111In. Three novel CHDT-functionalized PSMA inhibitors were synthesized and their Al18F-, 68Ga-, and 111In-labeled analogs were subjected to a detailed in vitro radiopharmacological characterization. Stability studies in vitro in human serum revealed among others a high kinetic inertness of all radiometal complexes. Furthermore, the Al18F-labeled PSMA ligands were characterized for their biodistribution in a LNCaP derived tumor xenograft mouse model by PET imaging. One radioligand, Al[18F]F-CHDT-PSMA-1, bearing a small azidoacetyl linker at the glutamate-urea-lysine motif, provided an in vivo performance comparable to that of [18F]PSMA-1007 but with even higher tumor-to-blood and tumor-to-muscle ratios at 120 min p.i. Overall, our results highlight the suitability of the novel CHDT moiety for functionalization and radiolabeling of small molecules or peptides with Al18F, 68Ga, and 111In and the triazole ring seems to entail favorable pharmacokinetic properties for molecular imaging purposes.