MR Signal Amplification for Receptor Imaging

MRamp策略最初设计的目的是提高MR的分子灵敏度 通过同时在两个水平上调制MR信号输出进行成像：1）靶特异性：一对 受体靶向酶共定位在特定的组织区室中， 互补，能够快速修饰低分子量顺磁性底物， 它们在反应部位的局部保留;和2）灵敏度：局部保留引起放大的MR信号 产生的高局部浓度密度和增加弛豫的顺磁性产品的 酶促反应我们已经在使MRamp技术更接近临床应用方面取得了重大进展 翻译包括：1）在人类病理学中内源性髓过氧化物酶活性的MRI证明 以及在各种疾病模型中; 2）在癌症模型中受体表达的成功成像。Mramp是一个 少数现有技术能够检测两种蛋白质标记物（受体）的共表达。 我们最近探索了除MRI外还使用µPET-CT进行共表达成像的可行性。通过实施 扩展的多模态成像方法（BLI、MRI和µPET-CT），我们之前发现溶骨性和 非溶骨性三阴性乳腺癌（TNBC）表型，并使用以下分析进行表征： 关键基因转录本这里提出的研究新阶段将包括双受体的优化 成像策略及其在TNBC的两种至关重要的生物标志物的体内成像中的应用，即 过表达EGFR和PD-L1。对TNBC中这些关键标志物的共表达进行成像的能力 肿瘤有望提供一种新的、高度可量化和易于解释的诊断成像方法 可用于（1）检测转移扩散，（2）选择患者进行靶向治疗，以及（3）监测 在治疗过程中的治疗反应或抵抗。除了简化监测外， 对于正在接受现有癌症治疗的患者，这种新方法可以加速研究性药物的测试。 因此，加快了有前景的新TNBC疗法的批准。我们最初的目标是 筛选新的嵌合小分子催化剂-底物，以选择最高MR和PET信号的候选物 使用我们的酶依赖性成像系统进行扩增。我们以前曾发表过关于 我们设计的MR可检测顺磁性Mn（II）为基础的超氧化物歧化酶模拟物，并将进一步 利用他们的力量来改造我们的磁共振放大器系统。这种小型化可能被证明是必不可少的， 在体内标记和追踪细胞外囊泡（EV）的能力，现在认为这是细胞外囊泡（EV）的关键因素。 转移性扩散的癌症，如TNBC。因此，本提案的第二个主要目标是 使用我们的双受体、高灵敏度酶互补方法，

The MRamp strategy was initially designed with the goal of improving the molecular sensitivity of MR imaging by modulating the MR signal output on two levels simultaneously: 1) target specificity: a pair of receptor-targeted enzymes co-localize in the specific tissue compartment and due to enzymatic activity complementation, enable rapid modification of low molecular weight paramagnetic substrates which results in their local retention at the reaction site; and 2) sensitivity: local retention gives rise to an amplified MR signal generated by both high local concentration density and increased relaxivity of the paramagnetic products of the enzymatic reaction. We have marked major milestones in bringing the MRamp technique closer to clinical translation including: 1) demonstration of MRI of endogenous myeloperoxidase activity in human pathology and in various disease models; 2) successful imaging of receptor expression in cancer models. MRamp is one of the few existing techniques enabling the detection of the co-expression of two protein markers (receptors). We recently explored co-expression imaging feasibility with µPET-CT in addition to MRI. By implementing an expanded multi-modality imaging approach (BLI, MRI and µPET-CT), we previously identified osteolytic and non-osteolytic triple-negative breast cancer (TNBC) phenotypes and characterized them using the analysis of key gene transcripts. The new phase of research proposed here, will include the optimization of a dual receptor imaging strategy and its application to in vivo imaging of two critically important biomarkers of TNBC, i.e. overexpressed EGFR and PD-L1. The ability to image the co-expression of these critical markers in TNBC tumors is expected to provide a new, highly quantifiable and easily interpretable diagnostic imaging method that can be used to (1) detect metastatic spread, (2) select patients for targeted therapies and (3) monitor therapeutic response or resistance over the course of treatment. In addition to simplifying the monitoring of patients undergoing existing cancer treatments, this new methodology could speed testing of investigational new drugs in clinical trials thus expediting approval of promising new TNBC therapies. Our initial goal will be to screen novel chimeric small molecule catalyst-substrates, to select candidates for highest MR and PET signal amplification using our enzyme dependent imaging system. We have previously published on inroads made in our design of MR detectable paramagnetic Mn(II)-based superoxide dismutase mimetics and will further harness their power as tools for miniaturizing our MRamp system. Such miniaturization may prove essential for the ability to tag and track extracellular vesicles (EV) in vivo which are now believed to be a key element in the metastatic spread of cancers such as TNBC. Therefore, a second major goal of this proposal will be to image endogenously occurring EVs using our dual receptor, high sensitivity enzyme complementation approach.