High-throughput radiochemistry platform for accelerated discovery and development of novel PET imaging agents for cancer

项目摘要/摘要 正电子发射断层扫描(PET)是一种先进的成像技术，依靠注入放射性物质 “示踪剂”，成像活着的受试者的特定生化过程。通过开发适当的示踪剂，PET可以 提供细胞表面标记/受体的丰度、酶的活性程度或 生物过程的速率。这些测量有助于了解癌症的生物学，发现和 开发新药，并为临床试验或临床决策提供关键信息。虽然很基本 研究发现了许多新的癌症标志物和潜在的治疗靶点 用于成像这些目标的合适的PET示踪剂的开发通常落后数年。 从识别候选示踪剂的文库筛选等方法开始，对候选进行排名 基于体外标准(如亲和力、选择性)。由于成本较高，这些候选人中只有极少数人 通常被贴上标签以供进一步评估。这导致缓慢的、递增的示踪剂开发过程， 体外选择标准与体内表现没有很好的相关性，这一问题加剧了这一问题。这项建议 旨在通过使在体内进行更大规模的筛查变得实用和负担得起来解决这一问题 候选库。 已经存在用于生成(未标记的)候选示踪剂文库的高通量方法，并且 高通量体内成像的潜力也已有报道。但是，目前还不存在 以高通量方式执行中间步骤的实用方法，即快速标记 复合库。这不仅是因为缺乏高通量的放射合成技术，而且 传统的放射合成方法体积大，导致前驱体成本高，比容量低 活动。 微流控放射化学的最新进展，其中的反应是在微升尺度的液滴中进行， 可以克服所有这些限制。该方案利用这些优势来创建高吞吐量 无线电标记平台。目的1开发一种微流控反应阵列，可同时进行至少48个反应。 在目标2中，开发了一种液体输送系统，以高效和快速地分配前体、放射性标记剂 等根据需要添加到反应部位。在AIM 3中开发了一个集成的自动化系统，并使用 各种常用的贴标药剂。最后，在AIM 4中，UPLC层析和固相萃取板 被评估为执行高通量纯化和配方的潜在手段，因此合成的 示踪剂已经准备好注射了。最终，这项提议寻求使筛查成为一种实际的、常规的可用的 加速和降低新型PET示踪剂开发成本的工具。

PROJECT SUMMARY/ABSTRACT Positron emission tomography (PET) is an advanced imaging technique, relying on the injection of radioactive “tracers” to image specific biochemical processes in living subjects. By developing appropriate tracers, PET can provide measurements of the abundance of cell surface markers/receptors, degree of enzyme activity, or the rate of a biological processes. These measurements help understand the biology of cancer, discover and develop new drugs, and provide critical information for clinical trials or clinical decision making. Though basic research has led to the discovery of many new cancer markers and potential therapeutic targets, the development of suitable PET tracers to image these targets typically lags years behind. Beginning with approaches such as library screening to identify candidate tracers, the candidates are ranked based on in vitro criteria (e.g. affinity, selectivity). Due to high costs, only a very tiny number of these candidates are usually labeled for further evaluation. This leads to a slow, incremental tracer development process, exacerbated by the issue that in vitro selection criteria don't correlate well with in vivo performance. This proposal seeks to address this issue by making it practical and affordable to perform in vivo screening of much larger candidate libraries. High-throughput methods already exist for generation of (unlabeled) libraries of candidate tracers, and the potential for high-throughput in vivo imaging has also been reported. However, there does not currently exist a practical approach for performing the middle step in a high-throughput fashion, i.e. rapidly radiolabeling a compound library. This is due not only to the lack of technology for high-throughput radiosynthesis, but also the large volume used in conventional radiosynthesis methods, which leads to high precursor cost and low specific activity. Recent advances in microfluidic radiochemistry, in which reactions are performed in microliter-scale droplets, can overcome all of these limitations. This proposal leverages these advances to create a high-throughput radiolabeling platform. Aim 1 develops a microfluidic reaction array to perform at least 48 simultaneous reactions. In Aim 2, a liquid delivery system is developed to efficiently and rapidly distribute precursor, radiolabeling agent etc. to the reaction sites as needed. An integrated, automated system is developed in Aim 3 and validated using various commonly-used labeling chemistries. Finally, in Aim 4, UPLC chromatography and SPE plates are evaluated as potential means for performing high-throughput purification and formulation so the synthesized tracers are ready for injection. Ultimately, this proposal seeks to make screening a practical, routinely-available tool to accelerate and reduce the cost of novel PET tracer development.