Novel Antibacterials Targeting Gram-negative Nonfermenters

描述(由申请人提供)：该项目的总体目标是开发一种新型的广谱治疗药物，双(吲哚)铅系列，用于对抗革兰氏阴性非发酵菌。目前治疗方法的数量和有效性有限，药物开发管道中新型广谱抗生素的稀缺，以及这些细菌容易产生耐药性，这些都表明迫切需要开发能够对抗这些病原体的更有效、更有效的新的抗菌剂。这一新系列化合物具有广谱抗菌活性，对革兰氏阴性杆菌的生长有很强的抑制作用(MIC为0.2-3g/ml)，包括鲍曼不动杆菌、铜绿假单胞菌、洋葱伯克霍尔德氏菌和嗜麦芽窄食单胞菌等革兰氏阴性非发酵菌。这些化合物对挑剔的革兰氏阴性杆菌和大量肠杆菌科菌株以及各种革兰氏阳性细菌也具有活性。它们通过快速杀菌机制发挥作用，在接近MIC值的浓度下，在1-4小时内显示出3对数的杀灭能力。确切的作用机制尚不清楚；然而，铅系列已被证明抑制通透性细菌细胞中的DNA复制，并抑制纯化的细菌复制DNA解旋酶。我们还未能分离出对主要铅支架MBX 1066或其类似物MBX 1162具有抗性的突变体。铅系列对革兰氏阴性感染的小鼠模型(即鼠疫耶尔森氏菌、假鼻疽伯克霍尔德氏菌；ED50和lt；10 mg/kg)有效。此外，这些化合物在小鼠体内耐受性良好(MTD=400 mg/kg)。最后，这些化合物的合成相对容易且价格低廉，而且具有非常有利的商品成本。这些总体特征促使这些化合物作为广谱抗菌剂迅速发展，用于治疗难以治疗的革兰氏阴性细菌病原体。我们将在合理的药物发现工作中对双(吲哚)铅系列进行化学优化，最初专注于提高广谱效力，同时将哺乳动物的细胞毒性降至最低。我们将在鲍曼不动杆菌引起的肺炎的小鼠模型中证明其有效性。在该项目的第二阶段，我们将通过至少两种老鼠感染模型(肺炎和皮囊)来扩展体内特征，然后对两种适合提交IND的物种进行IND使能(GLP)药代动力学、毒理学和安全药理学研究。公共卫生相关性：由革兰氏阴性非发酵菌引起的传染病，如鲍曼不动杆菌，由于这些微生物的多重耐药频率而难以治疗。它们越来越多地出现在医院和社区获得性感染中，以及在伊拉克和阿富汗战场上获得的感染中。这项提案描述了一种合理的方法，以双-(咪唑啉吲哚)系列化合物为靶点，该系列化合物是由USAMRIID和MicroBiotix的一个研究小组发现的一系列有效的抗菌剂，方法是创建更有效的化合物并测试它们的体外和体内活性。

DESCRIPTION (provided by applicant): The overall objective of this project is to develop a novel chemical class of broad-spectrum therapeutic agents, the bis-(indole) lead series, for use against Gram-negative nonfermenters. The limited number and efficacy of current therapies, the scarcity of novel broad-spectrum antibiotics in the drug development pipeline and the ease with which these bacteria develop drug resistance, argue for the urgent development of new more potent, broad-acting antibacterial agents capable of combating these pathogens. Compounds in this new chemical series exhibit broad-spectrum antibacterial activity, displaying potent (MIC's of 0.2-3 ?g/ml) inhibition of the growth of Gram-negative bacterial species, including such Gram-negative nonfermenters as Acinetobacter baumannii, Pseudomonas aeruginosa, Burkholderia cepacia and Stenotrophomonas maltophilia. These compounds are also active against fastidious Gram- negative bacilli and a large number of strains from the Enterobacteriaceae family as well as a variety of Gram-positive bacterial species. They act by a rapid bactericidal mechanism, exhibiting 3-log's of killing in 1-4 hours at concentrations near the MIC values. The precise mechanism of action is unknown; however, the lead series has been shown to inhibit DNA replication in permeabilized bacterial cells and to inhibit purified bacterial replicative DNA helicase. We have not been able to isolate mutants resistant to the primary lead scaffold MBX 1066 or its analog MBX 1162. The lead series is effective in murine models of Gram-negative infections (i.e., Yersinia pestis, Burkholderia pseudomallei; ED50 <10 mg/kg). In addition, the compounds are well-tolerated in mice (MTD =400 mg/kg). Finally, these compounds are relatively easy and inexpensive to synthesize, with a very favorable cost of goods. These overall characteristics advocate for the rapid development of these compounds as broad spectrum antibacterial agents for use against difficult-to-treat Gram-negative bacterial pathogens. We will chemically optimize the bis-(indole) lead series in a rational drug discovery effort focused initially on improving broad-spectrum potency while minimizing mammalian cytotoxicity. We will demonstrate efficacy in vivo in a murine model of A. baumannii-induced pneumonia. In Phase II of this project, we will expand upon the in vivo characterization with at least two rat infection models (pneumonia and skin pouch) and then conduct IND-enabling (GLP) pharmacokinetic, toxicology and safety pharmacology studies in two species suitable for IND submission. PUBLIC HEALTH RELEVANCE: Infectious disease caused by the Gram-negative nonfermenters, such as Acinetobacter baumannii, are difficult to treat due to the frequency of multi-drug resistance in these organisms. They are increasingly found in hospital and community-acquired infections as well as those infections obtained in the battlefields of Iraq and Afghanistan. This proposal describes a rational approach for targeting these bacterial agents with the bis-(imidazolinylindole) series of compounds, a series of potent antibacterials, discovered by a group at USAMRIID and Microbiotix, by creating more potent compounds and testing them for in vitro and in vivo activity.