Novel mycobacterial translocase I inhibitors - a new class of anti-TB drugs

描述（由申请人提供）：当今治疗结核病（TB）的医生迫切需要新的、高效的和有效的抗生素，以改善多药耐药（MDR）和无并发症结核病的治疗时间和治愈持久性。在已完成的i期批准（最终报告见下文）中，我们评估了一种令人兴奋的候选新药SQ641。SQ641具有优于异烟肼（INH）和所有其他结核病药物的活性，并且在适当的条件下，在我们的两种最佳结核病模型中迅速减少分枝杆菌；巨噬细胞和小鼠。我们简要地描述了药物的特性，包括其特殊的杀菌活性，它的靶点和作用机制（Translocase I），以及我们迄今为止开发口服制剂的努力。在该2期申请中，我们概述了下一步的工作，以确定一种商业上可行的SQ641口服制剂，用于口服治疗方案，以及一种可能创造新治疗范例的注射制剂；在诊断时给予的单次肠外剂量。与目前的结核病护理标准相比，制剂和相关治疗方案都将显著而迅速地减少组织中的细菌，并大幅缩短和改善结核病治疗时间。INH作为结核病治疗的基础药物用于强化化疗的前2个月，因为它能够快速杀死感染组织中快速复制的结核分枝杆菌（MTB），并减少肺分泌物中感染性细菌的数量。早期杀菌活性（EBA）临床研究证明，INH显然是目前所有可用的结核病药物中最有效的。有趣的是，与SQ641相比，INH是一种相对缓慢的体外作用药物，需要数天才能杀死MTB，并且抗生素后效应（PAE）仅为17小时。基于相对较短的半衰期，该药每天给药。尽管每天给药，最近的研究表明，活菌的数量仍然足以促进生理性（Siddiqi et al. 2007）和基因型耐药细菌。暴露于INH 48小时后，约10%的MTB被杀死，但形态仍完好无损。相比之下，SQ641在这段时间内杀死了90%的MTB，并且细菌被裂解（液体培养物是清晰的）。此外，SQ641的PAE为55小时，是INH的3倍。防止耐药性的最好方法是在细菌有机会适应药物之前迅速采取行动。SQ641在体外预防耐药突变体的发展方面非常有效，并且在体外与几种抗结核药物（乙胺丁醇（EMB）、链霉素和新的后遗症药物SQ109）具有显著的协同作用。SQ641对耐药和耐多药MTB、堪萨斯分枝杆菌、脓肿分枝杆菌和鸟分枝杆菌具有良好的体外活性，也可用于治疗非结核分枝杆菌（NTM）疾病。尽管SQ641对分枝杆菌具有显著的抗生素特性，但一种实用的方法来传递这种药物仍然是一个挑战。我们发现SQ641激活巨噬细胞中的p -糖蛋白（P-gp）药物外排泵，因此在感染的哺乳动物中这些携带MTB的重要细胞内不会积累到杀菌浓度。正如预期的那样，P-gp外排抑制剂显著增强了SQ641对细胞内MTB的活性；SQ641相当于或优于INH（该试验系统中最有效的单药）。在小鼠中，口服SQ641吸收不良。出于多种原因（患者可接受性、便利性和成本），口服给药是实施结核病治疗的首选方法。较差的生物利用度加上巨噬细胞的快速外排意味着要创造性地思考给药。幸运的是，我们通过将SQ641与维生素E类似物TPGS结合解决了外排和不溶性问题，TPGS通常用于提高药物溶解度和生物利用度（EASTMAN and Company 2005）。稳定,4 - 6 ?构建了m（分枝杆菌大小）sq641的TPGS颗粒。这些颗粒容易被巨噬细胞吞噬，并在吞噬体内释放SQ641，有效地杀死细胞内MTB。在巨噬细胞和TB小鼠模型中，SQ641/TPGS制剂与INH一样有效。在这个2期提案中，我们将评估各种方法（化学改性以提高溶解度，改变药物- p -gp相互作用，开发适当的商业给药系统）来溶解SQ641并优化其体内给药。我们将探索配方，以确定这种强效抗菌药物是否可以口服（与目前的标准治疗结核病药物联合使用，或作为其中一种或多种药物的替代品）和/或是否应该通过肠外给药，以启动结核病化疗，并在结核病强化治疗阶段提供早期和长期的细菌清除。

DESCRIPTION (provided by applicant): Physicians treating tuberculosis (TB) today are in desperate need of new, efficient, and effective antibiotics to improve both time of treatment and durability of cure in multi-drug resistant (MDR) as well as uncomplicated TB. In the completed Phase 1 grant (Final Report below), we evaluated an exciting new drug candidate, SQ641. SQ641 has activity superior to Isoniazid (INH) and all other TB drugs and, under appropriate conditions, rapidly reduces Mycobacteria in our two best TB disease models; macrophages and mice. We briefly describe the drug properties, including its exceptional bactericidal activity, its target and mechanism of action (Translocase I), and our efforts to date to develop an oral formulation. In this Phase 2 proposal, we outline the next steps to identify a commercially viable oral formulation(s) of SQ641 for oral treatment regimens, and a parenteral formulation(s) which would have the potential to create a new treatment paradigm; a single, parenteral dose administered at the time of diagnosis. Compared to the current standard of care for TB, both formulations, and associated treatment regimens would dramatically and quickly reduce bacteria in tissues and drastically shorten and improve TB treatment time. INH is used for the first 2 mo of intensive chemotherapy as a cornerstone drug of TB therapy because of its ability to quickly kill rapidly replicating Mycobacterium tuberculosis (MTB) in infected tissues and reduce the number of infectious bacteria in pulmonary secretions. As evidenced by Early Bactericidal Activity (EBA) clinical studies, INH is clearly the most potent of all currently available TB drugs. Interestingly, compared to SQ641, INH is a relatively slow-acting drug in vitro that requires several days to kill MTB, and has a post antibiotic effect (PAE) of only 17 hr. Based on a relatively short half- life, the drug is administered daily. Despite daily administration, recent studies demonstrate that the number of viable bacteria remains sufficient to promote physiologic (Siddiqi et al. 2007) and genotypic drug-resistant bacteria. After 48 hr of exposure to INH, ~10% of MTB are killed, but still morphologically intact. In contrast, SQ641 kills 90% of MTB in this timeframe and the bacteria are lysed (liquid cultures are clear). Moreover, SQ641 has a PAE of 55 hr, 3 times the INH PAE. The best way to prevent drug resistance is to act quickly, before bacteria have a chance to adjust to the presence of the drug. SQ641 is highly effective in preventing development of drug resistant mutants in vitro and has marked synergistic activity in vitro with several antituberculars: Ethambutol (EMB), streptomycin, and the new Sequella drug, SQ109. SQ641 has excellent in vitro activity against drug susceptible and MDR MTB, M. kansasii, M. abscessus, and M. avium, and could also be developed for nontuberculous mycobacterial (NTM) diseases. In spite of the remarkable antibiotic properties of SQ641 against Mycobacteria, a practical method to deliver this drug remains a challenge. We discovered that SQ641 activates the P-glycoprotein (P-gp) drug efflux pump in macrophages, and therefore does not accumulate to bactericidal concentrations inside these important cells that harbor MTB in infected mammals. As expected, P-gp efflux inhibitors markedly enhanced the activity of SQ641 against intracellular MTB; SQ641 was equivalent to or better than INH (the most potent single drug in this test system). In mice, orally administered SQ641 is poorly absorbed. For numerous reasons (patient acceptability, convenience, and cost), oral delivery is the preferred method to administer TB therapy. Poor bioavailability combined with rapid efflux from macrophages meant thinking creatively about drug delivery. Fortunately, we solved both efflux and insolubility problems by combining SQ641 with TPGS, a vitamin E analogue routinely used to improve drug solubility and hence bioavailability (EASTMAN and Company 2005). Stable, 4-6?m (~ the size of Mycobacteria) SQ641-containing TPGS particles were constructed. These particles were easily phagocytosed by macrophages and SQ641 was released inside phagosomes to efficiently and effectively kill intracellular MTB. In both macrophages and mouse models of TB, SQ641/TPGS formulation was as effective as INH. In this Phase 2 proposal, we will evaluate various methods (chemical modification to enhance solubility, alter drug-P-gp interactions, and develop appropriate commercial delivery systems) to solubilize SQ641 and optimize its delivery in vivo. We will explore formulations to determine whether this potent antimicrobial can be delivered orally (combined with current standard-of-care TB drugs or as a replacement for one or more of these drugs) and/or should be delivered parenterally to initiate TB chemotherapy and provide early and prolonged bacterial clearance during the intensive phase of TB treatment.