Accelerating the discovery and development of neurotracers via high-throughput radiochemistry

项目摘要/摘要 不断发现新的生物靶点提供了极大地改善我们的 了解疾病和正常功能，为治疗提供新的途径。这些细胞的活体成像 正电子发射断层扫描(PET)是一种特别有力的工具来理解起爆和 它有助于疾病的发展，并有助于开发新的治疗方法。PET的主要优点是 非常高的灵敏度(能够成像稀有目标，如神经感受器，而不会使它们饱和)，以及 对深层组织成像的能力(这提供了从临床前研究到后来临床使用的可译性)。 但开发有用和有效的示踪剂可能需要数年或数十年的时间。一个重要的限制因素是 放射化学的复杂性和成本，以及使用现有技术优化合成的难度 条件-以足够的产量实现可靠生产的关键一步，以支持最初的成像研究。 低产量和高试剂和高同位素消耗意味着优化研究非常昂贵 而且非常耗时，因此这种研究往往非常有限，不太可能找到全局最优的 条件。这些限制还在新探测器开发的其他方面造成压力，例如 努力减少“命中”的数量，因此只有很少的化合物被标记和 通过体外和体外试验以及体内成像进行研究。然而，这一遴选过程并不完美，因为它 有时会导致追求死胡同，同时将有前途的候选人排除在外。 为了更快地利用新生物靶点的临床前和临床成像，放射化学领域正在 迫切需要新的工具来改进示踪剂的发现和开发过程。我们提出的解决方案是 高通量放射化学方法的发展。最近，一系列的液滴反应 介绍了一种从一批放射性同位素快速并行执行数十个反应的方法， 这些反应的总试剂消耗类似于传统系统上的单个批次。此外， 液滴反应可以很容易地扩展到临床前甚至临床成像的数量。这些方法 可以在几天内有效地探索巨大的反应参数空间(而不是几周来 几个月)，或者它们可以用于并行标记数十个候选化合物以进行基于 最相关的指标：体内特性。虽然这些反应阵列使用手动移液操作， 已经揭示了高通量放射化学的好处和潜力，这项新技术需要 重大的进一步发展和自动化，以提高安全性和速度，并减少人类 错误。我们建议(1)集成原位辐射探测器，以量化每个阶段的放射性 反应，(2)集成自动采样反应进行分析的方法(RADIO-TLC或RADIO-UPLC)， 以及(3)使用高通量方法优化合成目前产率较低的5种神经示踪剂， 开发至少一种新的示踪剂，并开发放化高通量优化的最佳实践。

PROJECT SUMMARY/ABSTRACT The continuous discovery of new biological targets presents opportunities to dramatically improve our understanding of diseases and normal function and provides new avenues for treatment. In vivo imaging of these targets via positron-emission tomography (PET) is an especially powerful tool to understand the initiation and progression of disease and to aid in the development of novel therapeutics. The major benefits of PET are the very high sensitivity (enabling imaging of rare targets such as neuroreceptors without saturating them), and the ability to image deep tissues (which provides translatability from preclinical research to later clinical use). But the development of useful and validated tracers can take years or decades. A significant limiting factor is the complexity and cost of radiochemistry, and the difficulty in using current technologies to optimize synthesis conditions – a key step toward achieving reliable production with sufficient yield to support initial imaging studies. Slow throughput and high reagent and isotope consumption mean that optimization studies are very expensive and time-consuming, and thus such studies tend to be very limited and are unlikely to find globally optimal conditions. These limitations also create pressures in other aspects of new probe development, e.g., significant efforts are made to reduce the number of “hits” so only a very small number of compounds are labeled and studied via in vitro and ex vivo assays and in vivo imaging. However, this selection process is imperfect as it sometimes leads to the pursuit of dead-ends while it excludes promising candidates. To more rapidly leverage preclinical and clinical imaging of new biological targets, the radiochemistry field is in urgent need of new tools to improve the tracer discovery and development process. Our proposed solution is the development of high-throughput radiochemistry methods. Arrays of droplet reactions have recently been introduced as a way to rapidly perform dozens of reactions in parallel from a single batch of radioisotope, with total reagent consumption of those reactions similar to a single batch on a conventional system. Furthermore, the droplet reactions can readily be scaled to quantities for preclinical or even clinical imaging. These methods could be used to efficiently explore a vast reaction parameter space in a matter of days (instead of weeks to months), or they could be used to label dozens of candidate compounds in parallel to perform screening based on the most relevant metric: in vivo properties. While these reaction arrays, operated using manual pipetting, have revealed the benefits and potential of high-throughput radiochemistry, this new technology requires significant further development and automation to increase safety and speed, and reduce the chance for human error. We propose to (1) integrate in situ radiation detectors to quantify the radioactivity at various stages of each reaction, (2) integrate a method to automatically sample the reactions for analysis (radio-TLC or radio-UPLC), and (3) use high-throughput methods to optimize the synthesis of 5 neurotracers that currently have low yield, develop at least one novel tracer, and develop best practices for high-throughput optimization in radiochemistry.