Dual imaging and therapeutic targeting agents for glioblastoma

描述（由申请人提供）：脑癌是15岁以下儿童和34岁以下年轻人的第二大死亡原因。恶性胶质瘤是最常见的原发性脑肿瘤，尽管采用了包括手术切除、放疗和化疗在内的多种治疗手段，但仍有很大程度上无法治愈。确实需要开发新的治疗剂（例如，靶向治疗）和诊断剂，这种可怕的疾病。这项研究的长期目标是开发临床上有用的胶质母细胞瘤双重成像和治疗靶向药物。整合素是肿瘤显像和治疗的潜在靶点。整合素1321是胶质瘤细胞表面表达的主要整合素同种型。通过用全细胞结合方法筛选“一珠一化合物”（OBOC）组合肽库，我们最近鉴定了几种针对1321整联蛋白的环肽配体。这些肽的修饰导致鉴定出针对恶性人胶质母细胞瘤A-172和U-87 MG细胞系的更有效的肽配体LXY 1（环状cdGLG-Hyp-Nc，Hyp=羟脯氨酸）。体内光学成像显示小鼠皮下和原位U-87 MG异种移植物中的高肿瘤摄取。在这项研究中，我们计划使用OBOC组合库方法来进一步优化先导化合物LXY 1。将选择高效和特异性配体，首先使用光学成像，然后使用microPET成像，评价小鼠皮下和原位U-87 MG异种移植物的体内肿瘤靶向和生物分布研究。由于64 Cu适用于PET成像和放射治疗，因此我们假设，当与金属螯合剂CB-TE 2A缀合并用64 Cu标记时，用于胶质母细胞瘤结合的完全优化的LXY 1衍生物可以开发成新的癌症靶向PET成像和胶质母细胞瘤放射治疗剂。64 Cu-CB-TE 2A-肽的治疗效果超出了当前R21提案的范围。如果成功，有效和灵敏的PET显像剂可用于胶质母细胞瘤的早期检测和诊断，以及治疗试验中肿瘤反应的替代标记物或终点。 公共卫生相关性：在这项拟议的研究中，高度有效和特异性的胶质母细胞瘤细胞结合肽将通过集中的一珠一化合物库方法进行鉴定。当用64 Cu放射性标记时，这样的肽可以开发成临床上有用的双重PET成像和胶质母细胞瘤的放射性靶向剂。MicroPET将用于在原位和皮下异种移植小鼠模型中评估肽对胶质母细胞瘤的癌症靶向潜力。

DESCRIPTION (provided by applicant): Brain cancer is the second leading cause of death in children under age 15 and in young adults up to age 34. Malignant glioma, the most common type of the primary brain tumors, remains largely incurable despite intensive multimodality treatments including surgical resection, irradiation and chemotherapy. There is a definite need for the development of novel therapeutic (e.g., targeted therapy) and diagnostic agents for this dreadful disease. The long-term goal of this proposed research is to develop clinically useful dual imaging and therapeutic targeting agents for glioblastoma. Integrins are potential targets for tumor imaging and therapy. Integrin 1321 is the major intergrin isotype expressed on the surface of glioma cells. Through screening "one-bead one- compound" (OBOC) combinatorial peptide libraries with a whole cell binding approach, we recently identified several cyclic peptide ligands against 1321 integrin. Modification of these peptides led to identification of a more potent peptide ligand, LXY1 (cyclic cdGLG- Hyp-Nc, Hyp=hydroxyproline), against malignant human glioblastoma A-172 and U- 87MG cell lines. In vivo optical imaging showed high tumor uptake in both subcutaneous and orthotopic U-87MG xenografts in mice. In this proposed research, we plan to use OBOC combinatorial library approaches to further optimize the lead compound LXY1. Highly potent and specific ligands will be selected to evaluate for in vivo tumor targeting and biodistribution studies in both subcutaneous and orthotopic U-87MG xenografts in mice, first using optical imaging and later microPET imaging. Because 64Cu is suitable for both PET imaging and radiotherapy, we hypothesize that fully optimized LXY1 derivatives for glioblastoma binding, when conjugated to a metal chelator CB-TE2A and labeled with 64Cu can be developed into new cancer-targeted PET imaging and radiotherapeutic agents for glioblastoma. Therapeutic effects of 64Cu-CB-TE2A-peptide are beyond the scope of this current R21 proposal. If successful, efficient and sensitive PET imaging agents can be used for early detection and diagnosis of glioblastoma, as well as a surrogate marker or end point for tumor response in therapeutic trials. PUBLIC HEALTH RELEVANCE: In this proposed research, highly potent and specific glioblastoma cell binding-peptides will be identified by focused one-bead one-compound library approaches. Such peptides, when radiolabeled with 64Cu, can be developed into clinically useful dual PET imaging and radiotherapeutic targeting agents for glioblastoma. MicroPET will be used to evaluate the cancer targeting potential of the peptides for glioblastoma in an orthotopic and subcutaneous xenograft mice model.