Engineered antibody fragments for PET imaging of immunotherapeutic targets in gliomas

项目概要/摘要 没有有效的非侵入性诊断成像方法来准确分层和监测 免疫治疗在成人和儿童胶质瘤中的应用PET成像，利用放射性标记的抗体片段， 与放射性金属稳定螯合的微抗体（Mb）或双抗体（Db）是安全有效的免疫治疗的有希望的选择。 直接定量神经胶质瘤患者的细胞表面标志物，其反映动态免疫过程， 直接影响免疫效力。然而，PET分子成像的发展， 用于指导免疫治疗的标记物尚处于起步阶段。这个应用程序的长期目标是翻译 用于非侵入性诊断成像的有效的基于抗体片段的放射性示踪剂 免疫疗法对免疫疗法患者的临床决策产生有意义的影响。整体 本申请的目的是验证放射性示踪剂组合物在监测中的独特情况 在患者相关的鼠胶质瘤模型中的免疫疗法。这项研究的基本原理是， 使用放射性示踪剂定量重要免疫靶点、活化T细胞的侵入性诊断成像， 免疫抑制细胞，以防止和缩短无效治疗的持续时间。核心假设是 放射性标记的CD 11b、EphA 2和CD 69、基于抗体的PET示踪剂可以有效指导免疫治疗 恶性神经胶质瘤在目标1中，将通过PET用Cu-64标记的抗CD 11b抗体定量胶质瘤模型中的CD 11b。 CD 11b Mb/Db用于在TAMC之前和期间定量免疫抑制性肿瘤相关骨髓细胞（TAMC）- 有针对性的免疫疗法。在目的2中，临床前PET将用于定量在小鼠中的EphA 2表达水平。 神经胶质瘤EphA 2是一种高度相关的临床免疫治疗靶标，将作为“原理证明”抗原， 为开发全面的抗原PET策略提供基础。Cu-64-的标准摄取值（SUV） 标记的抗EphA 2 Mb/Db将用于在同源原位模型中定量神经胶质瘤细胞上的EphA 2水平 与一系列EphA 2水平，并确定神经胶质瘤荷瘤小鼠，将响应免疫疗法。在目标3中， 对神经胶质瘤免疫治疗的应答将通过具有Cu-64标记的抗CD 69 Mb/Db的CD 69 PET来评估， 量化T细胞活化并预测T细胞介导的胶质瘤小鼠的存活率 免疫疗法使用稳健的成像探针化学、成人和儿童鼠胶质瘤模型， 免疫治疗方法，将验证新的人/小鼠交叉反应性Mb/Db的翻译 容量如果成功的话，这一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成像来确定招募哪些受试者以及何时 停止或继续治疗。这项研究的结果将大大提高免疫治疗的反应率 同时减少不必要的治疗相关的副作用，无效和昂贵的治疗， 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.