Developing a pretargeting strategy to detect Fe(II) for nuclear medicine applications

开发用于核医学应用检测 Fe(II) 的预靶向策略

• 批准号: 10608162
• 负责人: Michael John Evans
• 金额: $ 64.21万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10608162
• 关键词: Abdomen; Acute; Animal Model; Animals; Antimalarials; Artemisinins; Benchmarking; Biodistribution; Biological; Cardiovascular Diseases; Cell Line; Cells; Chemicals; Child; Chloroquine; Clinical; Clinical Trials; Coupling; Data; Desmoplastic; Development; Discipline of Nuclear Medicine; Disease; Dose; Dose Limiting; Drug Kinetics; Exhibits; Generations; Genetic; Glioma; Goals; Half-Life; Hepatobiliary; Human; Image; ImmunoPET; In Vitro; Inductively Coupled Plasma Mass Spectrometry; Injections; Iron; KRASG12D; Knowledge; Libraries; Liver; Lysosomes; Malignant Neoplasms; Measurement; Measures; Modeling; Multifocal Lesion; Mus; Neurodegenerative Disorders; Normal Cell; Normal tissue morphology; Nutrient; PET/CT scan; Pancreas; Pancreatic Ductal Adenocarcinoma; Pathology; Pharmaceutical Preparations; Pharmacology; Physiology; Positron-Emission Tomography; Prodrugs; Radioisotopes; Reaction; Reagent; Refractory; Regulation; Role; Series; Serum; Signal Transduction; Starvation; Techniques; Testing; Therapeutic; Tissues; Toxic effect; Tracer; U251; analog; antimicrobial; cancer type; catalyst; clinically relevant; cohort; design; image translation; imaging modality; imaging study; improved; in vivo; inhibitor; innovation; insight; iron metabolism; liver cancer model; mouse model; optical imaging; pancreatic cancer model; pharmacologic; protein crosslink; prototype; radioligand; radiotracer; response; sensor; small molecule; subcutaneous; success; targeted treatment; tumor; uptake; virtual

Project Abstract While it has been recognized for decades that diseased cells arising from numerous disorders exhibit altered iron metabolism compared to normal cells, only recently has it become apparent that increased concentration of cytosolic free ferrous iron (Fe2+) - the labile iron pool (LIP) – is most associated with these pathologies. Meanwhile, the overwhelming clinical success of the antimalarial artemisinin has established that LIP can be safely exploited to treat diseases in humans (including children), a milestone that has inspired us and others to develop 1,2,4-trioxolane (TRX)-based prodrugs that are activated by LIP and release drug payloads within diseased cells. Although our knowledge of the role of LIP in normal physiology and disease has increased substantially over the past 10 years, virtually all of our insights about LIP are founded on observations from cell lines. Studying LIP in vivo is a major knowledge gap that is currently impeding efforts to apply experimental LIP targeted therapies clinically. We hypothesized based on the well-studied mechanisms of TRX reactivity with LIP that a PET strategy could enable LIP measurements in vivo by sequestering a radioisotope within cells via Fe(II)-dependent protein crosslinking. We designed a prototype, 18F-TRX, and showed that its biodistribution in vivo is Fe2+-dependent, it detects diverse cancer types with an expanded LIP, and tumor uptake of 18F-TRX is directly proportional to tumor response to LIP targeting therapies. However, the tracer's rapid serum clearance (t1/2 ~28 sec) and slow hepatobiliary clearance combine to limit the overall image quality. Thus, the goal of this project is to test if a pre-targeting strategy involving macrodosing of a cold TRX reagent, followed later by a microdose of a cognate 18F-click coupling partner may improve measurements of LIP by eliminating the background signal from unreacted TRX and/or achieving better TRX exposure in tissues with LIP expansion. During Aim 1, we will synthesize and study the in vivo pharmacology of TRX- transcyclooctene (TCO) conjugates and fluoro-tetrazines to identify optimal biorthogonal click partners. During Aim 2, the optimal pre-targeting conditions will be established in tumor bearing mice using immunoPET. Imaging findings (e.g. tumor uptake, tumor to normal ratios) will be benchmarked against 18F-TRX and the 18F- tetrazine alone. During Aim 3, we will perform cohort expansion studies to acquire additional biological replicates while also studying spontaneous and orthotopic tumor models arising in abdominal tissues (e.g. liver, pancreas) that we expect to be occult on 18F-TRX imaging. If successful, defining which disease types harbor high LIP with PET provides a natural segue to clinical trials implementing the myriad experimental LIP targeted therapies currently waiting in the queue. Solving this challenge with pre-targeting would also add a new application for a venerable dosing strategy that could be broadly applied to improve the image quality of other rapidly clearing small molecule radiotracers, or perhaps even the antitumor efficacy of radioligand therapies.

项目摘要 虽然几十年来已经认识到，由许多疾病引起的病变细胞表现出改变的 与正常细胞相比，铁代谢，直到最近才变得明显， 细胞溶质游离亚铁（Fe 2+）-不稳定铁库（LIP）-与这些病理学最相关。 与此同时，抗疟药物青蒿素的压倒性临床成功已经证明，LIP可以 安全地用于治疗人类疾病（包括儿童），这是一个里程碑，激励我们和其他人 开发基于1，2，4-三恶茂烷（TRX）的前药，其被LIP激活并在 病变细胞虽然我们对LIP在正常生理和疾病中的作用的认识有所增加， 在过去的10年里，几乎所有关于LIP的见解都是建立在对细胞的观察上的。 线在体内研究LIP是一个主要的知识差距，目前阻碍了实验性应用的努力。 LIP靶向治疗临床。我们假设基于TRX反应性的充分研究机制 对于LIP，PET策略可以通过将放射性同位素隔离在体内来实现LIP测量。 细胞通过Fe（II）依赖性蛋白质交联。我们设计了一个原型，18F-TRX，并表明其 体内的生物分布是Fe 2+依赖性的，它检测具有扩展LIP的不同癌症类型，并且肿瘤 18 F-TRX的摄入与肿瘤对LIP靶向治疗的反应成正比。但是追踪器 快速的血清清除（t1/2 ~28秒）和缓慢的肝胆清除联合收割机结合限制了整体图像 质量.因此，本项目的目标是测试是否预先靶向策略涉及冷TRX的大剂量给药 试剂，随后是微剂量的同源18F-点击偶联配偶体，可以改善对18F-点击偶联配偶体的测量。 通过消除未反应TRX的背景信号和/或实现组织中更好的TRX暴露来实现LIP LIP扩展在目标1中，我们将合成并研究TRX-1的体内药理学。 使用反式环辛烯（TCO）缀合物和氟-四嗪来鉴定最佳的双正交点击配偶体。期间 目的2、建立荷瘤小鼠免疫PET预靶向的最佳条件。 将以18F-TRX和18F-TRX为基准，对成像结果（例如肿瘤摄取、肿瘤与正常比值）进行基准评估。 单独的四嗪。在目标3期间，我们将进行队列扩展研究， 同时还研究了在腹部组织中产生的自发和原位肿瘤模型（例如， 肝脏，胰腺），我们预计在18F-TRX成像上是隐藏的。如果成功，确定哪些疾病类型 带有PET的Harbor高LIP为实施无数实验性LIP的临床试验提供了一个自然的过渡 目前正在排队等待的靶向治疗。通过预先定位解决这一挑战还将增加一个 一种古老的给药策略的新应用，可广泛应用于改善 其他快速清除的小分子放射性示踪剂，或者甚至放射性配体的抗肿瘤功效 治疗