Multimeric Ligands for Targeting Melanoma

描述（由申请人提供）：拟议工作的目标是开发用于转移性黑色素瘤靶向成像和治疗的异戊价药物。这些药物含有两种配体，可引导结构体与两种不同的细胞表面受体交联，从而显著增加结合选择性。这比针对单一受体的药物有优势，因为它们不依赖于单个细胞表面蛋白的过度表达。与其他多功能制剂相比，所提出的构建物也具有优势，因为它们是通过聚合合成产生的，并且设计成相对较小，具有有利的ADME特性。在支持的第一个阶段的工作已经(1)确定并验证了一种受体组合，可以用于靶向转移性黑色素瘤的一个子集，(2)证明了合成的异价药物可以交联异源受体的原理证明。与相应的单价相互作用相比，这些结构结合的亲和力高达50倍。目前的研究将结合这两种进展来开发针对已确定的靶受体对的异二价药物。为了实现这一目标，Aim 1将使用先前开发的g蛋白偶联受体（GPCR）系统来获得预测多价配体作为显像剂行为的分析解决方案。Aim 2将开发针对第一阶段确定的受体组合的二价药物：n -甲酰基肽受体样，2型（FPRL2）和1型黑素皮质素受体（MC1R）。在这个目标中，最佳的连接体和配体化学将通过高通量结合测定来确定。二价配体将用荧光团标记，用于细胞内和体内成像测试。具有最佳特征的将被标记为DOTA。DOTA衍生物将用于螯合Eu进行体外荧光和111In进行体内SPECT评估药代动力学和生物分布。Aim 3将继续对在第一期支持期间确定为靶点的另外21个受体进行验证。这些将主要通过组织微阵列的免疫组化来验证，该组织微阵列包含多个黑色素瘤等级以及多个正常组织。预计这项工作将导致验证其他受体组合，将针对大多数转移性黑色素瘤。在下一阶段的支持结束时，我们将(1)开发更精确的分析方法来预测多价配体作为显像剂的行为；(2)开发了靶向配体，可用于治疗40-50%的转移性黑色素瘤；(3)为该疾病的剩余分子表型确定了额外的3-和4-受体靶向组合。本研究的目标是为转移性黑色素瘤的成像和治疗提供靶向药物平台。这些药物是异二价的，因为它们将两个针对两种不同细胞表面受体的配体连接在一起。这种药物与针对单一表位的药物相比，具有不依赖于单一过表达的细胞表面蛋白的优势。与其他多功能制剂相比，它们还具有优势，因为它们是通过聚合合成产生的，因此相对较小，具有可接受的ADME特性。

DESCRIPTION (provided by applicant): The goal of the proposed work is to develop heterobivalent agents for targeted delivery of imaging and therapy to metastatic melanoma. These agents contain two ligands that direct the construct to crosslink two different cell surface receptors, resulting in dramatic increases in binding selectivity. This has advantages over agents directed against single receptors in that they do not rely on overexpression of a single cell surface protein. The proposed constructs also have advantages over other multifunctional agents in that they are produced via convergent synthesis and are designed to be relatively small with favorable ADME characteristics. Work during the first period of support has (1) identified and validated a receptor combination that can be used to target a subset of metastatic melanomas, and (2) demonstrated a proof-of-principle that synthetic heterobivalent agents can crosslink heterologous receptors. These constructs bound with up to 50-fold higher affinity compared to corresponding monovalent interactions. Current research will combine these two advances to develop heterobivalent agents against an identified target receptor pair. To achieve this goal, Aim 1 will use a previously developed G-protein coupled receptor (GPCR) system to derive analytical solutions that predict behavior of multivalent ligands as imaging agents. Aim 2 will develop bivalent agents that target a receptor combination identified in the first period of support: N-formyl peptide receptor like, type 2 (FPRL2) and the type 1 melanocortin receptor (MC1R). In this aim, optimum linker and ligand chemistries will be determined with high-throughput binding assays. Bivalent ligands will be labeled with fluorophores for testing by in-cyto and in-vivo imaging. Those with optimum characteristics will be labeled with DOTA. DOTA derivatives will be used to chelate Eu for ex vivo fluorescence and 111In for in vivo SPECT assessment of pharmacokinetics and biodistribution. Aim 3 will continue the validation effort for 21 additional receptors that were identified as targets during the first period of support. These will be validated primarily though immunohistochemistry of tissue microarrays containing multiple melanoma grades as well as multiple normal tissues. It is expected that this work will result in the validation of additional receptor combinations that will target a majority of metastatic melanomas. At the end of this next period of support, we will have (1) developed more precise analytical methods to predict the behavior of multivalent ligands as imaging agents; (2) developed targeting ligands that will be useful against 40-50% of metastatic melanomas and (3) identified additional 3- and 4-receptor target combinations for the remaining molecular phenotypes of this disease.The goal of the proposed work is to develop platform targeting agents for delivery of imaging and therapy to metastatic melanoma. These agents are heterobivalent in that they link together two ligands that are directed against two different cell surface receptors. Such agents have advantages over agents directed against single epitopes by not relying on a single overexpressed cell surface protein. They also have advantages over other multifunctional agents in that they are produced via convergent synthesis and hence are relatively small with acceptable ADME characteristics.