High-avidity multimeric cancer imaging agent

高亲合力多聚体癌症显像剂

• 批准号: 6931073
• 负责人: Anna M Wu
• 金额: $ 19.02万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6931073
• 关键词: antitumor antibody; athymic mouse; bioengineering /biomedical engineering; bioimaging /biomedical imaging; biotechnology; carcinoembryonal antigen; chelating agents; dimer; enzyme linked immunosorbent assay; immunologic substance development /preparation; iodine; neoplasm /cancer radioimmunotherapy; nucleic acid sequence; positron emission tomography; protein engineering; protein purification; radionuclide imaging /scanning; radionuclides; radiotracer; recombinant proteins; surface plasmon resonance; xenotransplantation

DESCRIPTION (provided by applicant) Cancer-targeting antibodies can provide a versatile starting point for generation of tumor-specific imaging agents. In particular, through protein engineering, recombinant antibody fragments can be produced that are optimized for in vivo tumor targeting, blood clearance, and normal tissue distribution and clearance patterns. Following conjugation and radiolabeling of such fragments with positron-emitting radionuclides such as Cu-64 and 1-124, engineered antibody fragments can be used for sensitive, high-resolution imaging in murine tumor xenograft models using small-animal imaging modalities such as microPET (positron emission tomography). We propose to develop high-avidity multimeric cancer imaging agents utlizing a novel protein multimerization technology. As a model system, single chain antibodies specific for carcinoembryonic antigen (CEA) will be reformatted to generate dimers and tetramers. 1) Following bacterial expression and purification biochemical and binding properties will be determined in vitro. 2) Recombinant antibodies will be labeled with radioiodine or conjugated with a chelating moiety (DOTA) for radiometal labeling for binding and biodistribution studies. Proteins will also be radiolabeled with 1-124 and Cu-64 for microPET imaging studies. In addition, a set of high-avidity multimeric anti-CEA antibody fragments modified with C-terminal Cys residues will be developed for site-specific conjugation and radiolabeling. 3) Performance of the antibody agents will be evaluated in athymic mice bearing CEA-positive (LS1741) and CEA-negative (C6) xenografts, in biodistribution studies and by serial microPET imaging studies in living mice. 4) The tumor targeting biodistribution, and imaging potential of the novel antibody constructs will be evaluated. The dimer and tetramer will be compared to determine whether the high avidity imparted by four binding domains enhances overall in vivo performance. The novel fragments will also be evaluated against existing antibody formats. Knowledge gained through this work will accelerate the development of cancer-specific imaging agents derived from any of a variety of antibodies specific for tumor-associated antigens, for single-photon or PET imaging applications.

描述（由申请人提供） 癌症靶向抗体可以为肿瘤特异性成像剂的产生提供通用的起点。特别地，通过蛋白质工程，可以产生针对体内肿瘤靶向、血液清除和正常组织分布和清除模式优化的重组抗体片段。在用正电子发射放射性核素如Cu-64和I-124缀合和放射性标记此类片段后，工程化抗体片段可用于使用小动物成像模式如microPET（正电子发射断层扫描）在鼠肿瘤异种移植物模型中进行灵敏的高分辨率成像。我们提出利用一种新的蛋白质多聚化技术开发高亲合力多聚体癌症显像剂。作为一个模型系统，特异性癌胚抗原（CEA）的单链抗体将被重新格式化，以产生二聚体和四聚体。1)在细菌表达和纯化之后，将在体外确定生物化学和结合特性。2)重组抗体将用放射性碘标记或与螯合部分（DOTA）缀合，用于结合和生物分布研究的放射性金属标记。蛋白质也将用1-124和Cu-64放射性标记，用于microPET成像研究。此外，将开发一组用C-末端Cys残基修饰的高亲合力多聚体抗CEA抗体片段用于位点特异性缀合和放射性标记。3)将在携带CEA阳性（LS 1741）和CEA阴性（C6）异种移植物的无胸腺小鼠中、在生物分布研究中以及通过活体小鼠中的系列microPET成像研究评价抗体药剂的性能。4)将评估新抗体构建体的肿瘤靶向生物分布和成像潜力。将比较二聚体和四聚体以确定由四个结合结构域赋予的高亲合力是否增强总体体内性能。还将针对现有抗体形式评价新片段。通过这项工作获得的知识将加速癌症特异性成像剂的开发，这些成像剂来源于对肿瘤相关抗原具有特异性的各种抗体中的任何一种，用于单光子或PET成像应用。