Multimeric Ligands for Targeting Melanoma

描述（由申请人提供）：拟定工作的目标是开发用于转移性黑色素瘤成像和治疗靶向递送的异二价药物。这些试剂含有两种配体，其指导构建体交联两种不同的细胞表面受体，导致结合选择性的显著增加。这与针对单一受体的试剂相比具有优势，因为它们不依赖于单一细胞表面蛋白的过表达。所提出的构建体也具有优于其他多功能试剂的优点，因为它们通过收敛合成产生，并且被设计为相对较小，具有有利的ADME特征。在第一个支持期间的工作已经（1）确定并验证了可用于靶向转移性黑色素瘤子集的受体组合，以及（2）证明了合成异源二价剂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，这些构建体以高达50倍的亲和力结合。目前的研究将联合收割机这两个进步，开发异二价剂对确定的目标受体对。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成像剂的行为的分析解决方案。目标2将开发靶向第一阶段支持中鉴定的受体组合的二价药物：N-甲酰肽受体样2型（FPRL 2）和1型黑皮质素受体（MC 1 R）。在这个目标中，最佳的接头和配体化学将确定与高通量结合测定。二价配体将用荧光团标记，用于通过细胞内和体内成像进行测试。那些具有最佳特性的将被标记为DOTA。DOTA衍生物将用于螯合Eu用于离体荧光和111 In用于体内SPECT评估药代动力学和生物分布。目标3将继续对第一个支助期内确定为目标的另外21个受体进行验证。这些将主要通过含有多种黑色素瘤等级以及多种正常组织的组织微阵列的免疫组织化学进行验证。预计这项工作将导致对靶向大多数转移性黑色素瘤的其他受体组合的验证。在下一个支持期结束时，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）开发了可用于对抗40-50%的转移性黑素瘤的靶向配体，和（3）鉴定了另外的3-和4-所提出的工作的目标是开发平台靶向剂，用于转移性黑色素瘤的成像和治疗。这些试剂是异二价的，因为它们将针对两种不同细胞表面受体的两个配体连接在一起。此类试剂通过不依赖于单一过表达的细胞表面蛋白而具有优于针对单一表位的试剂的优点。它们还具有优于其他多功能剂的优点，因为它们通过收敛合成产生，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.