目的:越来越多的证据表明,神经降压素(NTS)和神经降压素受体(NTSR)通过触发多种致癌信号通路在肺癌的进展中起关键作用。本研究旨在开发具有成像和治疗应用潜力的Cu标记的神经降压素受体1(NTSR1)靶向剂。
方法:合成了一系列具有可变丙胺(PA)接头长度和不同螯合剂的神经降压素受体拮抗剂(NRAs),包括[64Cu]Cu-CB-TE2A-iPA-NRA([64Cu]Cu-4a-c,i=1,2,3),[64Cu]Cu-NOTA-2PA-NRA([64Cu]Cu-4d),[64Cu]Cu-DOTA-2PA-NRA([64Cu]Cu-4e,也称为[64Cu]Cu-3BP-227),和[64Cu]Cu-DOTA-VS-2PA-NRA([64Cu]Cu-4f)。在H1299肺癌模型中进行一系列小动物PET/CT。NTSR1的表达谱也通过使用患者组织样品的IHC确认。
结果:对于大多数研究的化合物,PET/CT显示突出的肿瘤摄取和高的肿瘤背景对比,但是肿瘤滞留受到使用的螯合剂的强烈影响。对于先前报告的4e,[64Cu]Cu标记的衍生物显示出最初的高肿瘤摄取,伴随着在24小时的快速肿瘤清除。新开发的[64Cu]Cu-4d和[64Cu]Cu-4f在早期时间点显示出良好的肿瘤摄取和肿瘤背景对比,但在肿瘤保留方面不太乐观。相比之下,我们的先导化合物[64Cu]Cu-4b在p.i.4、24和48h时表现出9.57±1.35、9.44±2.38和9.72±4.89%ID/g肿瘤摄取,分别。在大多数其他器官中,观察到中度肝脏摄取(在p.i.4、24和48h时,为11.97±3.85、9.80±3.63和7.72±4.68%ID/g),摄取较低。发现PA接头对药物分布具有显著影响。与[64Cu]Cu-4b相比,[64Cu]Cu-4a背景较低,包括肝脏摄取大大减少,而肿瘤摄取仅中度降低。同时,[64Cu]Cu-4c在肿瘤和肝脏中均显示出增加的摄取。NTSR1的临床相关性也由患者组织样品中升高的肿瘤表达证明。
结论:通过并排比较,[64Cu]Cu-4b基于其高和持续的肿瘤摄取和中等的肝脏摄取被鉴定为用于进一步评估的先导剂。它不仅可以有效地检测肺癌中NTSR1的表达(用于诊断,患者筛查,和治疗监测),而且一旦螯合β发射体67Cu,也具有治疗NTSR阳性病变的巨大潜力。
OBJECTIVE: Accumulating evidence suggests that neurotensin (NTS) and neurotensin receptors (NTSRs) play key roles in lung cancer progression by triggering multiple oncogenic signaling pathways. This study aims to develop Cu-labeled neurotensin receptor 1 (NTSR1)-targeting agents with the potential for both imaging and therapeutic applications.
METHODS: A series of neurotensin receptor antagonists (NRAs) with variable propylamine (PA) linker length and different chelators were synthesized, including [64Cu]Cu-CB-TE2A-iPA-NRA ([64Cu]Cu-4a-c, i = 1, 2, 3), [64Cu]Cu-NOTA-2PA-NRA ([64Cu]Cu-4d), [64Cu]Cu-DOTA-2PA-NRA ([64Cu]Cu-4e, also known as [64Cu]Cu-3BP-227), and [64Cu]Cu-DOTA-VS-2PA-NRA ([64Cu]Cu-4f). The series of small animal PET/CT were conducted in H1299 lung cancer model. The expression profile of NTSR1 was also confirmed by IHC using patient tissue samples.
RESULTS: For most of the compounds studied, PET/CT showed prominent tumor uptake and high tumor-to-background contrast, but the tumor retention was strongly influenced by the chelators used. For previously reported 4e, [64Cu]Cu-labeled derivative showed initial high tumor uptake accompanied by rapid tumor washout at 24 h. The newly developed [64Cu]Cu-4d and [64Cu]Cu-4f demonstrated good tumor uptake and tumor-to-background contrast at early time points, but were less promising in tumor retention. In contrast, our lead compound [64Cu]Cu-4b demonstrated 9.57 ± 1.35, 9.44 ± 2.38 and 9.72 ± 4.89%ID/g tumor uptake at 4, 24, and 48 h p.i., respectively. Moderate liver uptake (11.97 ± 3.85, 9.80 ± 3.63, and 7.72 ± 4.68%ID/g at 4, 24, and 48 h p.i.) was observed with low uptake in most other organs. The PA linker was found to have a significant effect on drug distribution. Compared to [64Cu]Cu-4b, [64Cu]Cu-4a had a lower background, including a greatly reduced liver uptake, while the tumor uptake was only moderately reduced. Meanwhile, [64Cu]Cu-4c showed increased uptake in both the tumor and the liver. The clinical relevance of NTSR1 was also demonstrated by the elevated tumor expression in patient tissue samples.
CONCLUSIONS: Through the side-by-side comparison, [64Cu]Cu-4b was identified as the lead agent for further evaluation based on its high and sustained tumor uptake and moderate liver uptake. It can not only be used to efficiently detect NTSR1 expression in lung cancer (for diagnosis, patient screening, and treatment monitoring), but also has the great potential to treat NTSR-positive lesions once chelating to the beta emitter 67Cu.