Novel glutamate conjugates for radiotargeting PSMA

描述（由申请人提供）： 在美国，与前列腺癌相关的高发病率和死亡率推动了放射免疫成像和放射免疫治疗新方法的发展。诊断和预后标志物的一种策略利用前列腺特异性膜抗原（PSMA），一种与前列腺上皮、前列腺肿瘤细胞和其他肿瘤类型的新血管系统相关的整合的跨膜糖蛋白，其也与释放神经递质谷氨酸的NAALDase（N-乙酰化α-连接的酸性二肽酶）高度同源。已经报道了一系列PSMA抑制剂，其基于两种基本结构，含有膦酸酯和次膦酸酯的过渡态类似物和通过简单脲键连接的新型二肽。本研究的一个目的是制备基于脲的抑制剂的衍生物，所述基于脲的抑制剂在不涉及与特异性口袋结合的末端处被修饰，所述特异性口袋具有含有适合于与{M（CO）3} *1核心（M = Tc和Re）配位的头部基团的氨基酸。 我们的方法依赖于我们最近开发的基于单氨基酸类似物（SAAC）的99 mTc-放射性标记肽的新方法，所述单氨基酸类似物（SAAC）经修饰以提供三个潜在的供体基团用于与{M（CO）3} *1核心（M = Tc或Re）的面螯合。我们已经证明了通过标准固相肽合成方案和随后的99 mTc和Re 28标记将SAAC快速和简单地引入生物活性肽。该提议的创新在于将单个氨基酸螯合剂并入PSMA抑制剂的现有药物化学知识库中，以便允许随后分别用99 mTc或186/1888 Re放射性同位素标记用于成像或治疗应用。 基于脲的类似物将由通过α-NH 2基团通过脲键与单个氨基酸螯合物偶联的谷氨酸组成。代表性的SAAC包括赖氨酸的e-衍生物。SAAC将在氨基末端用基于吡啶、咪唑、羧酸盐、硫醇盐和噻唑的供体基团衍生化。改变供体基团取代基将产生总电荷、疏水性和空间影响的变化。将制备一系列SAAC谷氨酸缀合物作为潜在的NAAG抑制剂，以评估诸如供体基团身份、系链长度和几何形状、空间影响和电荷等因素对酶抑制和结合的影响。 将制备缀合物的{Re（CO）3} *1复合物作为{Tc（CO）3} *1复合物的模型，并将其用于生物测定。使用由Tyco-Mallinckrodt，Inc.提供的Isolink TM试剂盒容易地制备99 mTc（CO）3（H2O）3 1核。将评价SAAC-脲-谷氨酸盐系列复合物的结合和抑制活性。将使用PSMA阳性和PSMA阴性细胞系进行细胞摄取研究。在评价这些结果后，将在含有PSMA阳性和PSMA阴性人前列腺肿瘤模型的小鼠中进一步研究在体外PSMA阳性细胞中表现出特异性结合的化合物。

DESCRIPTION (provided by applicant): The development of novel approaches for radioimmunoimaging and radioimmunotherapy is driven by the high incidence and mortality rate associated with prostate cancer in the United States. One strategy to diagnostic and prognostic markers exploits prostate-specific membrane antigen (PSMA), an integral transmembrane glycoprotein, associated with the prostate epithelium, prostatic tumor cells and the neovasculature of other tumor types, which is also highly homologous to NAALDase (N-acetylated a-Iinked acidic dipeptidase) which releases the neurotransmitter glutamate. A range of PSMA inhibitors have been reported, based on two fundamental structures, phosphonate and phosphinate containing transition state analogues and novel dipeptides connected through a simple urea linkage. One objective of the research is to prepare derivatives of the urea-based inhibitors modified at the terminus not involved with binding to the specificity pocket with an amino acid containing a head group suitable for coordination to the {M(CO)3} *1 core (M = Tc and Re). Our approach relies on our recently developed a novel approach to 99mTc-radiolabeling of peptides based on single amino acid analogues (SAAC) modified to provide three potential donor groups for facial chelation to the {M(CO)3} *1 core (M = Tc or Re). We have demonstrated the rapid and simple introduction of SAAC into bioactive peptides via standard solid phase peptide synthesis protocols and subsequent labeling with 99mTc and Re28 The innovation of this proposal is to incorporate single amino acid chelators into the existing medicinal chemistry knowledge base of inhibitors of PSMA, so as to allow subsequent labeling with 99mTc or 186/1888Re radioisotopes for imaging or therapeutic applications, respectively. The urea-based analogues will be comprised of a glutamate coupled to a single amino acid chelate by a urea linkage through the a-NH2 groups. Representative SAACs include e-derivatives of lysine. The SAACs will be derivatized at the amino terminus with donor groups based on pyridine, imidazole, carboxylate, thiolate and thiazole. Altering the donor group substituents will yield changes in overall charge, hydrophobicity and steric influence. A series of SAAC glutamate conjugates will be prepared as potential NAAG inhibitors allowing the assessment of the influence of factors such as donor group identity, tether length and geometry, steric influences and charge on enzyme inhibition and binding. The {Re(CO)3} *1 complexes of the conjugates will be prepared as models for the {Tc(CO)3} *1 complexes and will be used for biological assays. The 99mTc(CO)3(H20) 3}¿1core is readily prepared using the Isolink TM kit, which has been supplied by Tyco-Mallinckrodt, Inc. The SAAC-urea-glutamate series of complexes will be evaluated for binding and inhibitory activity. Cell uptake studies will be performed using PSMA-positive and PSMA-negative cell lines. Upon evaluation of these results, compounds that demonstrate specific binding in PSMA-positive cells in vitro will be studied further in mice containing both PSMA-positive and PSMA-negative human prostate tumor models.