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生成肿瘤特异性显像剂提供通用的起点。特别是，通过蛋白质工程，可以生产针对体内肿瘤靶向、血液清除以及正常组织分布和清除模式进行优化的重组抗体片段。将这些片段与 Cu-64 和 1-124 等正电子发射放射性核素缀合和放射性标记后，工程化抗体片段可用于使用 microPET（正电子发射断层扫描）等小动物成像方式在小鼠肿瘤异种移植模型中进行灵敏、高分辨率的成像。我们建议利用新型蛋白质多聚化技术开发高亲合力多聚体癌症成像剂。作为模型系统，癌胚抗原（CEA）特异性单链抗体将被重新格式化以产生二聚体和四聚体。 1) 细菌表达和纯化后的生化和结合特性将在体外测定。 2) 重组抗体将用放射性碘标记或与螯合部分 (DOTA) 缀合，用于放射性金属标记，用于结合和生物分布研究。蛋白质还将用 1-124 和 Cu-64 进行放射性标记，用于 microPET 成像研究。此外，还将开发一套用 C 端 Cys 残基修饰的高亲和力多聚抗 CEA 抗体片段，用于位点特异性缀合和放射性标记。 3) 抗体药物的性能将在携带 CEA 阳性 (LS1741) 和 CEA 阴性 (C6) 异种移植物的无胸腺小鼠中、生物分布研究和活体小鼠的系列 microPET 成像研究中进行评估。 4) 将评估新型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四个结合结构域赋予的高亲合力是否增强整体体内性能。新片段还将根据现有抗体形式进行评估。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，这些成像剂源自针对肿瘤相关抗原的各种特异性抗体，用于单光子或 PET 成像应用。