Identification of preclinical drug candidates for the treatment of schistosomiasis

治疗血吸虫病的临床前候选药物的鉴定

基本信息

批准号：
9813829
负责人：
Pavel A Petukhov
金额：
$ 49.07万
依托单位：
RUSH UNIVERSITY MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-12-01 至 2021-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9813829
关键词：
Adolescent Animal Model Antioxidants Binding Binding Sites Biochemical Biochemistry Biological Assay Biological Availability Cell Survival Cells Cessation of life Chemicals Chronic Disease Clinical Collaborations Complement Complex Computer Assisted Computer-Aided Design Country Crystallization Development Diagnostic Disease Drug Targeting Drug resistance Enzymes Evolution Funding Glutathione Reductase Human In Vitro Infection International Interruption Libraries Ligands Liver Microsomes Mammalian Cell Mediator of activation protein Medical Metabolic Molecular Molecular Target Morbidity - disease rate Mus Oral Oxadiazoles Oxidation-Reduction Oxides Parasite resistance Pharmaceutical Chemistry Pharmaceutical Preparations Pharmacology Pharmacotherapy Phase Plasma Praziquantel Praziquantel resistance Prevalence Property RNA Interference Recombinant Proteins Research Resistance Schistosoma Schistosome Parasite Schistosomiasis Selenocysteine Seminal Structure Study models TXN gene Toxic effect United States National Institutes of Health Vertebrates X-Ray Crystallography analog base candidate selection chemoproteomics chemotherapy cytotoxicity design disability drug candidate drug development drug discovery enzyme activity glutaredoxin high throughput screening improved in vivo inhibitor/antagonist innovation iterative design lead optimization mouse model neglect new therapeutic target next generation novel novel therapeutics pharmacokinetics and pharmacodynamics pre-clinical small molecule small molecule inhibitor structural biology thioredoxin reductase transmission process

项目摘要

PROJECT SUMMARY/ABSTRACT Schistosome parasites infect 200 million people, resulting in significant morbidity and more than 200,000 deaths annually. Schistosomiasis control strategies rely almost exclusively on chemotherapy and tens of millions of people are treated with the only available drug, praziquantel (PZQ). There are no new drugs in the clinical pipeline. PZQ cure rates obtained in mass drug administration campaigns are typically less than 50%. Furthermore, with projected levels of PZQ use it is inevitable that PZQ-resistant parasites will evolve. Therefore, it is imperative to identify new drug targets and drugs for schistosomiasis treatment. We identified a highly promising drug target: the worm selenocysteine-containing enzyme thioredoxin glutathione reductase (TGR). We established that TGR is a central and essential mediator of antioxidant defenses in the worm. The antioxidant defenses of vertebrates are diversified to three independent enzymes, glutathione reductase, thioredoxin reductase, and glutaredoxin, whereas schistosomes rely solely on TGR. TGR is a chokepoint and its inhibition leads to rapid worm death in all developmental stages. In contrast, PZQ has poor activity against juvenile worms, often resulting in partial cures. We have shown that TGR is druggable, can be selectively targeted over human orthologous enzymes and that its inhibition in worms in an animal model of schistosomiasis leads to worm death. PZQ analogs are inactive, restricting analog development to avoid or counteract drug resistance. Unlike PZQ for which the mechanism of action is not known, TGR is a defined molecular target, active as a recombinant protein, with established biochemical assays amenable to rapid compound analysis, SAR, and optimization. We recently completed a multi-tiered HTS of a large compound library (>350,000 compounds), which identified >100 TGR inhibitors that were inactive against off-target, orthologous human enzymes and nontoxic to mammalian cells. The identification of these hits demonstrates that specific inhibitors of TGR can be obtained without off-target interactions and cytotoxicity. We have obtained both liganded and ligand-free crystal structures of TGR, allowing a structure based approach to hit optimization. We hypothesize that iterative medicinal chemistry optimization will yield potent and selective small molecule TGR inhibitors that will have in vivo worm killing activity. In the R21 phase our aims are to identify hits from the multi-tiered HTS with potent (< 5 µM) worm killing activity and to characterize the TGR binding site of these inhibitors by co-crystallization with TGR and crystal structure determination. In the R33 phase we propose to optimize these novel, potent TGR inhibitors using cutting-edge, structure and ligand- based computer-aided design and medicinal chemistry to improve potency, stability, and oral bioavailability. This will be complemented by X-ray crystallography and chemoproteomics using photoreactive probes to characterize molecular TGR-compound interactions. Medicinal chemistry will be informed by enzymatic analysis of TGR and orthologous human enzymes, metabolic stability, in vitro cell toxicity, and activity against ex vivo worms. Finally, select compounds will be assessed for PK/PD properties and efficacy against schistosome infections in mice. To accomplish these transformative aims, an innovative international collaboration of global experts with expertise in schistosome biochemistry and drug discovery, structural biology, computer-aided molecular design, and chemoproteomics has been assembled. The varied and synergistic expertise of the team will facilitate overcoming critical barriers to drug development. Completion of the project will identify preclinical drug-like compounds, suitable for candidate selection for schistosomiasis treatment.

项目概要/摘要血吸虫寄生虫感染 2 亿人，导致严重发病，超过 20 万人每年有数十人死亡，血吸虫病控制策略几乎完全依赖化疗。数百万人接受唯一可用的药物吡喹酮（PZQ）的治疗。该药物中没有新药。大规模药物管理活动中获得的临床管道中的 PZQ 治愈率通常低于 50%。此外，随着 PZQ 使用的预计水平，抗 PZQ 寄生虫将不可避免地进化。因此，寻找新的治疗血吸虫病的药物靶点和药物势在必行。极具前景的药物靶点：含有硒代半胱氨酸的蠕虫硫氧还蛋白谷胱甘肽还原酶 (TGR)。我们确定 TGR 是蠕虫抗氧化防御的核心和重要介质。脊椎动物的抗氧化防御多样化为三种独立的酶：谷胱甘肽还原酶，硫氧还蛋白还原酶和谷氧还蛋白，而血吸虫仅依赖 TGR 是一个阻塞点。它的抑制作用会导致所有发育阶段的蠕虫快速死亡，相反，PZQ 的抑制活性较差。我们已经证明 TGR 是可以药物治疗的，可以选择性地治疗幼虫。针对人类直系同源酶，并在动物模型中对蠕虫进行抑制血吸虫病导致蠕虫死亡，PZQ 类似物不活跃，限制类似物的开发以避免或与作用机制尚不清楚的 PZQ 不同，TGR 是一种明确的药物。分子靶标，作为重组蛋白具有活性，具有可快速检测的已建立的生化测定我们最近完成了大型化合物的多层 HTS。库（> 350,000 种化合物），其中识别出 > 100 种对脱靶无活性的 TGR 抑制剂，这些命中的鉴定证明是直系同源的人类酶并且对哺乳动物细胞无毒。我们已经获得了没有脱靶相互作用和细胞毒性的 TGR 特异性抑制剂。获得了 TGR 的配体和无配体晶体结构，从而允许基于结构的方法击中我们追求迭代药物化学优化将产生有效和选择性。在 R21 阶段，我们的目标是具有体内杀虫活性的小分子 TGR 抑制剂。识别来自多层 HTS 的具有有效 (< 5 µM) 蠕虫杀灭活性的命中，并表征 TGR 通过与 TGR 共结晶和 R33 晶体结构测定这些抑制剂的结合位点。我们建议使用尖端的结构和配体来优化这些新型、有效的 TGR 抑制剂基于计算机辅助设计和药物化学，以提高效力、稳定性和口服生物利用度。 X 射线晶体学和化学蛋白质组学将使用光反应探针来补充这一点通过酶促表征分子 TGR 与药物化学的相互作用。 TGR 和直系同源人类酶、代谢稳定性、体外细胞毒性和抗活性的分析最后，将评估选定化合物的 PK/PD 特性和针对蠕虫的功效。为了实现这些变革性的目标，一个创新的国际组织。具有血吸虫生物化学和药物发现、结构方面专业知识的全球专家的合作生物学、计算机辅助分子设计和化学蛋白质组学已经集结在一起。该团队的协同专业知识将有助于克服完成药物开发的关键障碍。该项目将鉴定适合血吸虫病候选药物选择的临床前药物化合物治疗。