Engineered antibody fragments for PET imaging of immunotherapeutic targets in gliomas

项目摘要/摘要 没有有效的非侵入性诊断成像方法来准确地分层和监测 成人和儿童脑胶质瘤的免疫治疗。PET成像，利用放射性标记的抗体片段， 微体(Mb)或双体(Db)，稳定地与放射性金属螯合，是一种安全有效的有前途的选择 胶质瘤患者细胞表面标志物的直接定量反映动态免疫过程 直接关系到免疫治疗的效果。然而，用于分子成像的正电子发射计算机断层扫描的发展 指导免疫治疗的标记物还处于初级阶段。此应用程序的长期目标是将 基于抗体片段的有效放射性示踪剂在非侵入性诊断成像中的应用 免疫治疗对免疫治疗患者的临床决策有意义的影响。整体而言 本应用程序的目的是验证放射性示踪剂组合物在监测中的独特情况 与患者相关的小鼠神经胶质瘤模型的免疫治疗。这项拟议研究的理由是 使用放射性示踪剂进行侵入性诊断成像，以量化重要的免疫靶点、激活的T细胞和 免疫抑制细胞，以防止和缩短无效治疗的持续时间。中心假设是 基于抗体的放射性标记CD11b、EphA2和CD69的PET示踪剂可以有效地指导免疫治疗 治疗恶性胶质瘤。在目标1中，CD11b将通过铜-标记的抗脑胶质瘤模型的正电子发射计算机断层扫描进行定量。 CD11b Mb/DB定量检测肿瘤相关髓系细胞(TAMC)免疫抑制 靶向免疫疗法。在AIM 2中，临床前PET将用于量化EphA2在 神经胶质瘤。EphA2是一种高度相关的临床免疫治疗靶点，将作为“原则证明”抗原，并 为制定全面的抗原-PET策略提供基础。铜--的标准吸收值 标记的抗EphA2 Mb/Db将用于同种异体原位模型脑胶质瘤细胞上EphA2水平的定量 检测一系列EphA2水平，并识别对免疫疗法有反应的胶质瘤小鼠。在《目标3》中， 用铜-标记的抗CD69Mb/Db的CD69PET评价对胶质瘤免疫治疗的反应 T细胞介导的胶质瘤荷瘤小鼠T细胞活化及存活率预测 免疫疗法。使用稳健的成像探针化学，成人和儿童小鼠胶质瘤模型，以及 免疫治疗方法，将验证新的人/鼠交叉反应Mb/Db的翻译 容量。如果成功，这项提议将从根本上改变神经胶质瘤的分层和监测方式 免疫治疗试验，使用实时分子PET成像来确定哪些受试者登记以及何时登记 停止或继续治疗。这项研究的结果将极大地提高免疫治疗的应答率 在减少不必要的治疗相关副作用、无效和昂贵的治疗的同时，在一个 精准医疗，增加治疗选择。

PROJECT SUMMARY/ABSTRACT There are no effective non-invasive diagnostic imaging approaches to accurately stratify and monitor immunotherapy in adults and children with glioma. PET imaging, utilizing radiolabeled antibody fragments, minibodies (Mb), or diabodies (Db), stably chelated to radiometals, is a promising option for the safe and effective direct quantification of cell surface markers in glioma patients that reflect dynamic immunological processes that bear directly on immunotherapeutic effectiveness. However, development of PET for molecular imaging of markers to guide immunotherapy is in its nascent stage. The long-term goal of this application is to translate effective antibody fragment-based radiotracers for non-invasive diagnostic imaging before and during immunotherapy to meaningfully impact clinical decision making for patients on immunotherapies. The overall objective of this application is to validate radiotracer compositions for unique situations in monitoring immunotherapies in patient-relevant murine glioma models. The rationale for the proposed research is that non- invasive diagnostic imaging with radiotracers quantifying an important immune target, activated T-cells, and immunosuppressive cells to prevent and shorten the duration of ineffective therapies. The central hypothesis is that radiolabeled CD11b, EphA2, and CD69, antibody-based PET tracers can effectively guide immunotherapies for malignant gliomas. In Aim 1, CD11b will be quantified in glioma models by PET with Cu-64-labeled anti- CD11b Mb/Db to quantify immunosuppressive tumor-associated myeloid cells (TAMC) before and during TAMC- targeted immunotherapies. In Aim 2 preclinical PET will be employed to quantify EphA2 expression levels in gliomas. EphA2, a highly relevant clinical immunotherapy target, will serve as a “proof of principle” antigen, and provide a base to develop comprehensive antigen-PET strategies. Standard uptake values (SUV) of Cu-64- labeled anti-EphA2 Mb/Db will be used to quantify EphA2 levels on glioma cells in syngeneic orthotopic models with a range of EphA2 levels and identify glioma-bearing mice that will respond to immunotherapies. In Aim 3, responses to glioma immunotherapy will be assessed by CD69 PET with Cu-64-labeled anti-CD69 Mb/Db to quantify T-cell activation and predict survival rates of glioma-bearing mice following T-cell-mediated immunotherapies. The use of robust imaging probe chemistry, adult and pediatric murine glioma models, and immunotherapy approaches, will validate novel human/mouse cross-reactive Mb/Db for their translational capacity. If successful, this proposal will radically change the way gliomas are stratified and monitored on immunotherapy trials, using real-time molecular PET imaging to determine which subjects to enroll and when to stop or continue therapy. Outcomes from this research will greatly improve response rates to immunotherapy while reducing unnecessary treatment-related side effects, ineffective and costly treatments, in an era of precision medicine with increased treatment options.