Preclinical development of a novel antibacterial for Clostridium difficile diseas

摘要 在Gram+DNA聚合酶抑制剂IIc和IIIe中，有几个化合物对多重 厌氧革兰氏+艰难梭菌(Cdiff)菌株。这些化合物似乎是有选择性的 Cdiff与其他革兰氏+厌氧菌和好氧菌比较，以及先导化合物-2-(3，4-二氯苯基)- 7-(5-吗啉戊基)鸟嘌呤或359E-口服有效地保护仓鼠免受致命的Cdiff感染。这个 感兴趣的化合物很难被口服吸收，而且太弱，不能被开发成系统地用来对抗 革兰氏+需氧菌感染。化合物359E及其类似物是叔胺，容易形成水溶性盐， 在体外和体内对Cdiff都有很好的抑制作用。鉴于梭状芽胞杆菌的流行日益增加 艰难梭菌相关性腹泻(CDAD)，包括由高毒力、毒素过度生产和/或抗生素引起的 对于耐药菌株，治疗这种疾病的新的和选择性的抗菌药的需求正在增长。我们的第二阶段 结果强烈表明，先导化合物的发展或作为口服治疗Cdiff的替代方案 人类患者的腹泻将导致一种新的、一流的药物来治疗这种新出现的传染病。 该项目竞争性更新的具体目标集中在359E的临床前开发上 或一种密切相关的先导化合物(LC)。目标是：1、扩大规模并开始流程开发 359E；2，确定作用机制、选择性、抗菌谱和耐药性发展 3、测定359E的口服安全性、抗梭菌效果及在仓鼠体内的吸收情况；4、合成 并筛选359E类似物作为备用LC化合物，并指定开发候选化合物(CD)。 一旦发生这种情况，将开始支持IND的研究。这些研究包括：5、体外ADME研究；6、 临床前分析、毒理学和毒代动力学研究；7、安全药理学和遗传毒性研究；8、 CGMP制作的CD。一旦所有临床前研究完成，目标9将涵盖 准备用于CD的IND应用，作为CDAD的口服治疗。 CDAD在美国和欧洲的发病率呈上升趋势，Cdiff是已确定的主要 曾使用过抗生素的患者发生医院内腹泻的感染原因。 万古霉素和甲硝唑是治疗CDAD的一线药物，但有报道称 治疗失败和甲硝唑治疗后的CDAD复发 美国疾病控制与预防中心(CDC)已不鼓励万古霉素在医院治疗CDAD，以尽量减少 耐万古霉素肠球菌和葡萄球菌的风险。各种治疗方法正在进行临床试验， Cdiff感染的临床前开发，从直接作用的抗菌药到疫苗和 中和Cdiff毒素的化合物。我们第二阶段研究的结果表明，很有可能 DNA聚合酶III抑制剂将成为治疗CDAD的一种有效且无毒的口服药物。

ABSTRACT Among inhibitors of Gram+ DNA polymerases IIIC and IIIE, several compounds are active against multiple strains of the anaerobic Gram+ bacterium Clostridium difficile (Cdiff). The compounds appear to be selective for Cdiff compared with other Gram+ anaerobes and aerobes, and a lead compound - 2-(3,4-dichlorobenzyl)- 7-(5-morpholinylpentyl)guanine or 359E - is active orally in protecting hamsters from lethal Cdiff infection. The compounds of interest are poorly absorbed orally and too weak to be developed for systemic use against Gram+ aerobe infections. Compound 359E and analogs are tertiary amines, readily form water soluble salts, and are highly effective against Cdiff in vitro and in vivo. Given the increasing prevalence of Clostridium difficile-associated diarrhea (CDAD), including that from highly virulent, toxin-overproducing and/or antibiotic- resistant strains, the need for new and selective antibacterials to treat this disease is growing. Our phase II results strongly suggest that development of the lead compound or an alternative as an oral treatment for Cdiff diarrhea in human patients will result in a novel, first in class drug to treat this emerging infectious disease. The specific aims of the competing renewal of this project are focused on preclinical development of 359E or a closely related lead compound (LC). The aims are to: 1, scale up and begin process development for 359E; 2, determine the mechanism of action, selectivity, anticlostridial spectrum, and resistance development of 359E; 3, determine oral safety, anti-clostridial efficacy, and absorption of 359E in the hamster; 4, synthesize and screen analogs of 359E as backup LC compounds, and designate a candidate for development (CD). Once this has occurred, IND-enabling studies will commence. These include: 5, in vitro ADME studies; 6, preclincal analytical, toxicology and toxicokinetic studies; 7, safety pharmacology and genotoxicity studies; 8, cGMP production of the CD. Once all preclinical studies have been completed, aim 9 will encompass preparation an IND application for the CD as oral treatment for CDAD. Incidence of CDAD is on the rise in the United States and Europe, and Cdiff is the major identified infectious cause of nosocomial diarrhea in patients to whom antibiotics had been previously administered. Vancomycin and metronidazole are first-line therapy for treatment of CDAD, but there have been reports of treatment failure and CDAD recurrence after treatment with metronidazole, and the Centers for Disease Control and Prevention (CDC) has discouraged vancomycin for treatment of CDAD in hospitals to minimize the risk of vancomycin-resistant enterococci and staphylococci. Various treatments are in clinical trials and preclinical development for Cdiff infections, ranging from direct-acting antibacterials to vaccines and compounds to neutralize Cdiff toxins. The results of our phase II studies indicated the strong likelihood that a DNA polymerase III inhibitor will be an effective and non-toxic oral treatment of CDAD.