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） 靶向癌症的抗体可以为产生肿瘤特异性成像剂的多功能起点。特别是，通过蛋白质工程，可以生产重组抗体片段，这些抗体片段可用于体内肿瘤靶向，血液清除以及正常组织分布和清除模式。在将这种片段与正电子放射性核素（如CU-64和1-124）结合和放射标记后，可以使用小动物异种成像模型（例如Micropet（PociTron）（Pocitron）（Pocitron poctron secisionran sission phosecraphy），可以将工程抗体片段用于敏感的，高分辨率的高分辨率成像。我们建议开发高避免性多聚体癌症成像剂，使新型蛋白质多聚化技术UTLE。作为模型系统，将重新格式化针对癌症抗原（CEA）的单链抗体，以生成二聚体和四聚体。 1）将在体外确定细菌表达和纯化生化和结合特性。 2）重组抗体将用放射碘标记或与螯合部分（DOTA）共轭用于放射性标记，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，以进行微型蛋白质成像研究。此外，将开发一组用C末端CYS残基修饰的高避免性多聚体抗CEA抗体片段，用于特定地点的共轭和放射性标记。 3）将在具有CEA阳性（LS1741）和CEA阴性（C6）异种移植物的无胸腺小鼠中评估抗体剂的性能，在生物分布研究中以及通过生物小鼠中的串行微型TEC研究。 4）将评估靶向生物分布的肿瘤和新型抗体构建体的成像潜力。将比较二聚体和四聚体，以确定四个结合结构域赋予的高热量是否会增强体内性能的总体性能。新颖的片段还将针对现有的抗体格式进行评估。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，这些成像剂源自单光子或PET成像应用，这些抗体针对肿瘤相关的抗原具有特定的各种抗体。