Cathespin K Radioligands for In Vivo Imaging

用于体内成像的 Cathespin K 放射性配体

基本信息

批准号：
8302276
负责人：
MICHAEL R KILBOURN
金额：
$ 17.49万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-07-15 至 2014-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8302276
关键词：
Accounting Adult Affect Affinity Age Aged, 80 and over Albers-Schonberg disease Alkylation Anatomy Animals Arthritis Binding Biodistribution Biological Assay Biological Markers Bone Diseases Bone Resorption Bone Tissue Bone remodeling Bromides Carbon Cathepsin L Cathepsins Cathepsins B Cells Chemicals Clinical Collagen Type I Cysteine Protease Degenerative polyarthritis Detection Development Dose Drug Kinetics Enzyme Inhibitor Drugs Enzyme Inhibitors Evaluation Exhibits Family Feedback Fluorine Fracture Grant Hip Fractures Human Image Imaging Techniques Implant In Vitro Injection of therapeutic agent Institutes Label Ligands Location Measures Metabolism Metastatic Osteosarcoma Molecular Monitor Morphology Musculoskeletal Musculoskeletal Diseases Nuclear Onset of illness Optical Methods Osteoclasts Osteolysis Osteolytic Osteoporosis Pathology Peptide Hydrolases Positron-Emission Tomography Process Publishing Radioactivity Radioisotopes Radiolabeled Rattus Reaction Regimen Reporting Rheumatoid Arthritis Rodent Rodent Model Series Societies Source Specificity TNFSF11 gene Techniques Therapeutic Toxicology Treatment Protocols United States Up-Regulation Woman amino group analog base bone bone loss cathepsin K cost design drug discovery hydroxyl group imaging modality improved in vivo inhibitor/antagonist methyl group methyl iodide molecular imaging novel novel diagnostics osteoclastogenesis prognostic indicator radioligand radiotracer receptor scaffold skeletal skeletal disorder standard measure therapeutic effectiveness tool uptake

项目摘要

DESCRIPTION (provided by applicant): Osteoporosis is estimated to affect over half of adults in the United States over the age of 50, and 1 in 3 women over the age of 80 will suffer a hip fracture; of those who fracture, nearly 15-20% die within 1 year. Overall, the costs associated with osteoporosis in the United States alone were estimated at $19 billion in 2005. This project involves the design, development and evaluation of an new molecular imaging radiotracers for Positron Emission Tomography (PET) studies of osteoporosis and other musculoskeletal diseases (e.g., osteoarthritis, rheumatoid arthritis, osteoporosis) involving potential bone loss. The project will develop radiolabeled forms of known high affinity inhibitors of cathepsin K, a cyteine protease that in highly expressed in osteoclasts and that is responsible for type I collagen degradation and bone resorption. The potential for in vivo imaging of cathepsin K has been demonstrated using optical methods, and this project will extend this concept to a clinically translatable imaging method using radionuclide labeling. This grant will prepare series of radiolabeled inhibitors based on the published cyanopyrimidine and pyrrolopyrimidine scaffolds, using isotopic (carbon-11) substitution or synthesis of fluorinated analogs (for fluorine-18 labeling). The compounds selected as initial targets for carbon-11 labeling all have high affinity for human cathepsin K (< 10 nanomolar), excellent selectivity over cathepsins L and S (100-1000 fold selective) and all are readily labeled using [11C]methyl iodide. New fluorinated analogs where fluoroethyl groups replace methyl groups will be evaluated in vitro for inhibitory action on cathepsin K enzymatic activity, using a fluorescent assay, and potent (<10 nM) inhibitors labeled using analogous [18F]fluoroalkylation reactions. In vivo proof of concept studies to demonstrate osteoclast-dependent localization of radiotracers will be done in rats using focal skeletal injections of RANKL (receptor activator for nuclear facktorB ligand, to induce osteoclastogenesis) or osteoprotogerin (to inhibit osteoclastogenesis). Extent of bone loss will be monitored by microCT. Verification that radioactivity localization is cathepsin-specific will be done in RANKL treated rats and blocking with cold doses of enzyme inhibitor. Successful radiotracers that exhibit high uptake and retention in RANKL-treated animals that is blocked by cold inhibitor, and reduced uptake in osteoprotegrin-treated animals, can then be further evaluated as potential radioligands for human imaging. Detection of increased osteoclastic cellular activity may provide new diagnostic criteria that take osteoclast activity into account in addition to standard measures of structural integrity, and thus provide immediate feedback on the efficacy of a chosen treatment protocol before waiting for further downstream gain or loss of bone to occur. .

描述（由申请人提供）：据估计，美国一半以上 50 岁以上的成年人都患有骨质疏松症，三分之一的 80 岁以上女性会发生髋部骨折；骨折患者中，近 15-20% 会在一年内死亡。总体而言，2005 年仅在美国，与骨质疏松症相关的费用就估计为 190 亿美元。该项目涉及设计、开发和评估一种新的分子成像放射性示踪剂，用于骨质疏松症和其他肌肉骨骼疾病的正电子发射断层扫描 (PET) 研究。例如，骨关节炎、类风湿性关节炎、骨质疏松症），涉及潜在的骨质流失。该项目将开发已知高亲和力组织蛋白酶 K 抑制剂的放射性标记形式，组织蛋白酶 K 是一种在破骨细胞中高度表达的半胱氨酸蛋白酶，负责 I 型胶原蛋白降解和骨吸收。组织蛋白酶 K 体内成像的潜力已通过光学方法得到证实，该项目将这一概念扩展到使用放射性核素标记的临床可转化成像方法。该资助将基于已发表的氰基嘧啶和吡咯并嘧啶支架，使用同位素（碳11）取代或合成氟化类似物（用于氟18标记）来制备一系列放射性标记抑制剂。选择作为碳 11 标记初始目标的化合物均对人组织蛋白酶 K（< 10 纳摩尔）具有高亲和力，比组织蛋白酶 L 和 S 具有优异的选择性（选择性 100-1000 倍），并且都很容易使用 [11C] 碘甲烷进行标记。将使用荧光测定法在体外评估其中氟乙基取代甲基的新氟化类似物对组织蛋白酶K酶活性的抑制作用，以及使用类似的[18F]氟烷基化反应标记的有效（<10nM）抑制剂。体内概念验证研究将在大鼠中使用 RANKL（核因子 B 配体的受体激活剂，以诱导破骨细胞生成）或骨原素（以抑制破骨细胞生成）进行局部骨骼注射，以证明放射性示踪剂的破骨细胞依赖性定位。骨质流失的程度将通过 microCT 进行监测。将在 RANKL 处理的大鼠中验证放射性定位是否具有组织蛋白酶特异性，并用冷剂量的酶抑制剂进行阻断。成功的放射性示踪剂在经 RANKL 治疗的动物中表现出高摄取和保留，并被冷抑制剂阻断，并且在经骨保护素治疗的动物中表现出低摄取，然后可以进一步评估其作为人类成像的潜在放射性配体。破骨细胞活性增加的检测可以提供新的诊断标准，除了结构完整性的标准测量之外，还考虑破骨细胞活性，从而在等待进一步的下游骨增加或损失之前提供有关所选治疗方案功效的即时反馈。发生。。