Beyer Darja, Vaccarin Christian, Schmid Jerome V, Deberle Luisa M, Deupi Xavier, Schibli Roger, Müller Cristina
Center for Radiopharmaceutical Sciences, PSI Center for Life Sciences, Forschungsstrasse 111, 5232 Villigen-PSI, Switzerland.
Condensed Matter Theory Group, PSI Center for Scientific Computing, Theory, and Data, 5232 Villigen-PSI, Switzerland.
Mol Pharm. 2025 Jun 2;22(6):3242-3254. doi: 10.1021/acs.molpharmaceut.5c00135. Epub 2025 May 6.
Several studies have focused on the development and application of radiolabeled DOTA-AE105 for targeting the urokinase-type plasminogen activator receptor (uPAR), which is expressed on various cancer types. The aim of this project was to design and evaluate novel uPAR-targeting radiopeptides with improved pharmacokinetic properties in view of their therapeutic application. Five peptides (uPAR-01, uPAR-02, uPAR-03, uPAR-04, and uPAR-05) were synthesized based on the AE105 peptide backbone, a DOTA chelator, and the 4-(-iodophenyl)butanoate moiety as an albumin binder. The peptides were obtained in 20-29 synthetic steps using solid-phase peptide synthesis with a 6-34% overall yield. In saline, the Lu-labeled peptides (100 MBq/nmol) were stable (>93% intact radiopeptides) in the presence of l-ascorbic acid over 24 h. The new radiopeptides were also stable (>98% intact radiopeptides) in mouse and human blood plasma, while only ∼13% of [Lu]Lu-DOTA-AE105 was intact after a 4 h incubation period. The uPAR-binding affinities ( values) determined with uPAR-transfected human embryonic kidney cells (HEK-uPAR) ranged from 10 to 57 nM and were, thus, similar to that of [Lu]Lu-DOTA-AE105 (: 20 ± 1 nM). Compared to [Lu]Lu-DOTA-AE105, the radiopeptides showed the anticipated increased binding affinity to plasma proteins both in mouse (31- to 104-fold) and human blood plasma (43- to 136-fold). The tissue distribution of the novel radiopeptides in nude mice bearing HEK-uPAR xenografts showed substantial activity retention in the blood (12-16% IA/g and 4.5-13% IA/g at 4 and 24 h p.i., respectively), while [Lu]Lu-DOTA-AE105 was rapidly cleared (<0.1% IA/g at 4 h p.i.). As a result, the accumulation of the new radiopeptides in HEK-uPAR xenografts (3.6-11% and 3.1-10% IA/g at 4 and 24 h p.i., respectively) was increased in comparison to that of [Lu]Lu-DOTA-AE105 (<1% IA/g at 4 h p.i.). Importantly, the metabolic stability of the new radiopeptides in mice was enhanced as compared to that of [Lu]Lu-DOTA-AE105. [Lu]Lu-uPAR-02 showed the most promising tissue distribution profile with over 10-fold higher activity retention in the HEK-uPAR xenograft than observed after injection of [Lu]Lu-DOTA-AE105. As a result, the xenograft-to-kidney ratio of [Lu]Lu-uPAR-02 was >3-fold higher than that of [Lu]Lu-DOTA-AE105.
多项研究聚焦于放射性标记的DOTA - AE105的开发与应用，以靶向尿激酶型纤溶酶原激活剂受体（uPAR），该受体在多种癌症类型中均有表达。鉴于其治疗应用，本项目的目的是设计并评估具有改善药代动力学性质的新型uPAR靶向放射性肽。基于AE105肽骨架、DOTA螯合剂以及作为白蛋白结合剂的4 -（-碘苯基）丁酸酯部分，合成了五种肽（uPAR - 01、uPAR - 02、uPAR - 03、uPAR - 04和uPAR - 05）。这些肽通过固相肽合成法经20 - 29个合成步骤获得，总产率为6 - 34%。在生理盐水中，100 MBq/nmol的镥标记肽在l - 抗坏血酸存在下24小时内稳定（>93%完整放射性肽）。新的放射性肽在小鼠和人血浆中也稳定（>98%完整放射性肽），而[镥]镥 - DOTA - AE105在孵育4小时后仅有约13%保持完整。用转染uPAR的人胚肾细胞（HEK - uPAR）测定的uPAR结合亲和力（ 值）范围为10至57 nM，因此与[镥]镥 - DOTA - AE105（ ：20 ± 1 nM）相似。与[镥]镥 - DOTA - AE105相比，这些放射性肽在小鼠（31至104倍）和人血浆（43至136倍）中对血浆蛋白的结合亲和力均有预期的增加。在携带HEK - uPAR异种移植瘤的裸鼠中，新型放射性肽的组织分布显示在血液中有大量活性保留（分别在注射后4小时和24小时为12 - 16% IA/g和4.5 - 13% IA/g），而[镥]镥 - DOTA - AE105被迅速清除（注射后4小时<0.1% IA/g）。结果，与[镥]镥 - DOTA - AE105相比，新型放射性肽在HEK - uPAR异种移植瘤中的蓄积增加（分别在注射后4小时和24小时为3.6 - 11% IA/g和3.1 - 10% IA/g）。重要的是，与[镥]镥 - DOTA - AE105相比，新型放射性肽在小鼠体内的代谢稳定性增强。[镥]镥 - uPAR - 02显示出最有前景的组织分布图谱，在HEK - uPAR异种移植瘤中的活性保留比注射[镥]镥 - DOTA - AE105后观察到的高10倍以上。结果，[镥]镥 - uPAR - 02的异种移植瘤与肾脏的比值比[镥]镥 - DOTA - AE105高3倍以上。
