Fast in vivo CLICK chemistries for PET imaging

描述(由申请人提供)：这项提议的主要目标是使用快速体内点击化学，使生物医学成像与亲和配体，如单抗。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翻译研究中进一步发展技能，并为活体成像领域做出重大贡献。从长远来看，候选人希望从化学家全面过渡到独立的生物医学研究科学家。候选人提议在哈佛/麻省理工学院系统生物学中心在拉尔夫·韦斯莱德博士博士的指导下实施这项提议。除了研究提案，他的职业发展计划还包括补充课程、指导阅读、杂志俱乐部、 出席并在几个研讨会和会议上发表演讲，对成像科学的实际接触，以及与他的导师和由Robert Langer教授、Mungi Bawendi教授和Marcelo Di Carli教授组成的咨询委员会的密切正式互动。 该研究计划旨在开发平台化学，以便一旦亲和配体回到他们的目标位置(即，亲和配体和成像报告的解偶联给药)，就可以在体内进行定位靶向。尽管到目前为止已经开发了大量的靶向配体，但靶向报告结构具有固有的药代动力学，这对于体内成像是不可取的。为了实现特定部位的偶联，候选人建议使用最近引入的四嗪/应变亲双烯环加成反应。这种极快的反应是高度选择性的，不可逆转的，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。其具体目标是：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)用于生物医学成像的体内点击标记。为了测试这种方法，候选者将创建针对A33糖蛋白的亲双烯亲和配体，A33糖蛋白是一种在人类结肠癌中高度表达的表面持久标记。携带原发癌和转移性结肠癌的小鼠将被注射亲双烯亲和配体。经过几天的清除后，将使用一个小的、容易清除的四嗪成像探头。PET成像将用于定量探针定位，该方法将进行优化，并与其他方法进行比较，如亲和配体的直接标记和代谢报告18氟脱氧葡萄糖。如果成功，In的发展 生物医学成像的体内化学“点击”将提供一种几乎通用的方法，用于几乎任何靶向亲和配体的体内成像。

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.