Novel and Kidney Selective AMPK Activators to Treat Polycystic Kidney Disease

 描述（由申请人提供）：常染色体显性遗传性多囊肾病（ADPKD）的特征是存在无数充满液体的囊肿，这些囊肿进行性增大，导致肾单位丢失和肾功能进行性下降。囊肿衬里上皮细胞的异常增殖和由于Cl-依赖性液体分泌导致的囊肿内液体积聚是囊肿生长的原因。在过去的15年里，PKD的研究已经获得了大量的信息，但仍然缺乏对如何有效治疗该病的了解。托伐普坦是一种血管加压素V2受体拮抗剂，在PKD动物模型中非常有效，并且在克里思试验的患者中显著减缓PKD进展;然而，该药物在一些患者中引起肝脏并发症，并且未被FDA批准用于治疗PKD。mTOR抑制剂，如雷帕霉素，也被认为是潜在的疾病修饰疗法，然而，这些药物的临床试验令人失望。一个问题是，在耐受性相对较好的浓度下，药物的循环浓度可能不会 足以抑制肾脏中的mTOR。最近，叶酸偶联的雷帕霉素显示出特异性靶向肾脏，因为前体药物被叶酸受体介导的内吞作用吸收并在肾细胞内裂解释放活性雷帕霉素。 NovaTarg与堪萨斯大学医学中心的肾脏研究所合作，确定了一种抑制囊肿生长的创新方法。利用NovaTarg的重点药物化学项目和KUMC PKD研究人员的专业知识，我们开发了肾脏特异性AMPK激活剂，通过p53和mTOR途径抑制ADPKD细胞增殖，以及CFTR介导的Cl-分泌驱动的液体分泌。我们的方法是基于新型双胍类化合物的合成，双胍类化合物是二甲双胍的类似物，其利用肾特异性有机阳离子转运蛋白2（OCT 2）进入肾细胞并激活囊肿衬里细胞中的AMPK。双胍类是非常碱性的化合物，需要OCT进入细胞，但二甲双胍本身不能区分OCT 1（肝脏）和OCT 2（肾脏）。二甲双胍在慢性肾脏疾病患者中使用的一个重要并发症是由于药物在肝脏中蓄积而发生乳酸酸中毒。因此，NovaTarg已经合成了>130种二甲双胍类似物，以鉴定通过OCT 2选择性转运至靶向肾细胞的双胍。早期先导化合物NT 1021激活人ADPKD细胞中的AMPK，导致抑制mTOR介导的细胞增殖和跨上皮Cl分泌。此外，NT 1021阻断体外囊肿形成 在胶原基质内培养的ADPKD细胞和离体Pkd-/-小鼠胚胎肾中囊肿样结构的扩增。我们认为，高OCT 2选择性双胍类药物将避免肝脏被OCT 1摄取，并显示出该患者人群所需的安全性特征。在SBIR的第一阶段，NovaTarg发现了一种高度OCT 2选择性的双胍NT 1096，它对OCT 2的选择性高于NT 1021，但效力不如NT 1021。在第二阶段，我们将合成NT 1096的衍生物，以进行命中-铅优化，并在临床前研究中评估该药物，并准备测试该药物的主要临床试验。

 DESCRIPTION (provided by applicant): Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the presence of innumerous fluid filled cysts that progressively enlarge, leading nephron loss and the progressive decline in renal function. Aberrant proliferation of the cyst-lining epithelial cells and the accumulation of fluid within the cysts du to Cl-dependent fluid secretion are responsible for the growth of the cysts. During the past fifteen years, there has been enormous amounts information gained from PKD research; however there is still a lack of understanding on how to effectively treat the disease. Tolvaptan, a vasopressin V2 receptor antagonist, was highly effective in animals models of PKD and significantly slow PKD progression in patients of the TEMPO trial; however, the drug caused liver complications is some patients and was not approved by the FDA for treatment of PKD. mTOR inhibitors, such as rapamycin, are also being considered as potential disease modifying therapies, however, clinical trials of these agents have been disappointing. One concern is that circulating concentrations of the drug at concentrations that are tolerated relatively well may not be sufficient to inhibit mTOR in the kidneys. Recently, folate-conjugated rapamycin was shown to specifically target the kidney since the pro drug was taken up by the folate receptor-mediated endocytosis and cleaved releasing the active rapamycin within the kidney cells. NovaTarg, in collaboration with the Kidney Institute at the University of Kansas Medical Center, has identified an innovative approach to inhibit cyst growth. Taking advantage of the focused medicinal chemistry program at NovaTarg and the expertise of the PKD investigators at KUMC, we have developed kidney-specific AMPK activators that inhibit ADPKD cell proliferation through p53 and the mTOR pathway, and fluid secretion driven by CFTR mediated Cl- secretion. Our approach is based on the synthesis of novel biguanides, analogues of metformin that utilize the kidney specific organic cation transporter 2 (OCT2) to enter kidney cells and to activate AMPK in the cyst-lining cells. Biguanides are very basic compounds which require OCTs for cellular entry, but metformin itself does not discriminate between OCT1 (liver) and OCT2 (kidney). An important complication of the use of metformin in patients with chronic kidney disease is the development of lactic acidosis due to the accumulation of the drug in the liver. Thus NovaTarg has synthesized >130 biguanide analogues of metformin to identify biguanides that are selectively transported by OCT2 to target kidney cells. An early lead compound, NT1021 activated AMPK in human ADPKD cells, leading to inhibition of mTOR- mediated cell proliferation and transepithelial Cl secretion. In addition, NT1021 blocked in vitro cyst formation of ADPKD cells cultured within a collagen matrix and the expansion of cyst-like structures in Pkd-/- mouse embryo kidneys ex vivo. We think that highly OCT2 selective biguanides will avoid liver uptake by OCT1 and display the safety profile required for this population of patients. During Phase 1 of the SBIR, NovaTarg discovered a highly OCT2-selective biguanide NT1096 that has higher selectivity for OCT2 than NT1021, but is not quite as potent. In Phase 2, we will synthesis derivatives of NT1096 for hit-to-lead optimization and evaluate the drug in preclinical studies and prepare for testing the drug is a proof-of-principal clinical trial.