Fast in vivo CLICK chemistries for PET imaging

描述（由申请人提供）：本提案的广泛目标是使用快速体内点击化学，以实现具有亲和配体（如单克隆抗体）的生物医学成像。候选人Neal Devaraj在化学领域接受了广泛的培训，现在希望过渡到生物医学研究。他的近期目标是通过沉浸在转化研究中进一步发展技能，并为体内成像领域做出重大贡献。从长远来看，候选人希望从化学家完全过渡到独立的生物医学研究科学家。候选人建议在哈佛/MGH系统生物学中心在Ralph Weissleder博士的指导下进行该提案。除了研究建议，他的职业发展计划包括补充课程，辅导阅读，期刊俱乐部， 他参加了几次研讨会和会议并发表演讲，实际接触了成像科学，并与他的导师和由Robert Langer教授、Moungi Bawendi教授和Marcelo Di Carli教授组成的咨询委员会进行了密切的正式互动。 该研究计划旨在开发平台化学，以允许亲和配体一旦归巢到其靶标（即亲和配体和成像报告分子的解耦给药），就可以进行位点特异性体内靶向。尽管迄今为止已经开发了大量的靶向配体，但是靶-报告基因构建体具有固有的药代动力学，这对于体内成像是不期望的。为了实现位点特异性偶联，候选人建议与最近引入的四嗪/紧张的亲二烯体环加成一起工作。这种极其快速的反应是高度选择性的，不可逆的，并且可以在生理条件下进行。该提案旨在建立在这一尖端技术的基础上，并开发用于正电子发射断层扫描（PET）分子成像的通用体内点击反应。具体目标是：1）开发和表征一组用于放射性同位素标记的快速“点击”反应; 2）追求用于生物医学成像的体内点击标记。为了测试这种方法，候选人将创建针对A33糖蛋白的亲二烯体亲和配体，A33糖蛋白是一种在人类结肠癌中高度表达的表面持久性标记物。携带原发性和转移性结肠癌的小鼠将注射亲二烯体亲和配体。在清除数天后，将施用小的、容易清除的四嗪成像探针。PET成像将用于定量探针定位，该方法将被优化并与其他方法进行比较，例如直接标记亲和配体和代谢报告分子18氟脱氧葡萄糖。如果成功的话， 用于生物医学成像的体内“点击”化学将提供用于实际上任何靶向亲和配体的体内成像的几乎通用的方法。 公共卫生相关性（由申请人提供）：该项目旨在开发生物医学成像的改进方法。如果成功的话，这将导致在疾病可治愈时更早地检测到疾病，改善对疾病状况的诊断，从而可以进行适当的治疗，以及确定新疗法有效性的更好工具。

DESCRIPTION (provided by applicant): The broad goal of this proposal is to use fast in vivo click chemistries to enable biomedical imaging with affinity ligands such as monoclonal antibodies. The candidate, Neal Devaraj, has received extensive training in the field of chemistry and now wishes to transition to biomedical research. His immediate goal is to further develop skill sets through immersion in translational research and to make significant contributions to the field of in vivo imaging. Long term, the candidate wishes to make a full transition from chemist to independent biomedical research scientist. The candidate proposes to carry out the proposal at the Harvard/MGH Center for Systems Biology under the mentorship of Dr. Ralph Weissleder MD PhD. In addition to the research proposal, his career development plan includes supplemental coursework, mentored readings, journal clubs, attendance and presentation at several seminars and conferences, practical exposure to the imaging sciences, and close formal interaction with both his mentor and an advisory committee consisting of Prof. Robert Langer, Prof. Moungi Bawendi, and Prof. Marcelo Di Carli. The research plan aims to develop platform chemistries to allow site specific in vivo targeting of affinity ligands once they have homed to their target (i.e. decoupled administration of affinity ligand and imaging reporter). Though a large number of targeting ligands have been developed to date, target-reporter constructs have inherent pharmacokinetics which are undesirable for in vivo imaging. To achieve site specific coupling, the candidate proposes to work with the recently introduced tetrazine/strained dienophile cycloaddition. This extremely rapid reaction is highly selective, irreversible, and can be performed in physiological conditions. The proposal aims to build on this cutting-edge technology and to develop generic in vivo click reactions for molecular imaging with positron emission tomography (PET). The specific aims are to 1) develop and characterize a panel of fast "click" reactions for radioisotope labeling and 2) pursue in vivo click labeling for biomedical imaging. To test this method, the candidate will create dienophile affinity ligands against A33 glycoprotein, a surface persistent marker that is highly expressed in human colon cancers. Mice bearing primary and metastatic colon cancer will be injected with dienophile affinity ligands. After several days of clearance, a small, readily cleared tetrazine imaging probe will be administered. Imaging with PET will be used to quantify probe localization and the method will be optimized and compared to other methods such as direct labeling of affinity ligands and the metabolic reporter 18fluorodeoxglucose. If successful, the development of in vivo "click" chemistry for biomedical imaging will provide a nearly universal methodology for in vivo imaging of virtually any targeting affinity ligand. PUBLIC HEALTH RELEVANCE (provided by applicant): This project aims to develop improved methods for biomedical imaging. If successful this would lead to detection of disease much earlier when they are curable, improved diagnosis of diseased condition so appropriate treatment can be administered, and better tools for determining the effectiveness of new therapies.