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）以及简单TB的治疗时间和治愈持久性。在完成的第一阶段资助（最终报告如下）中，我们评估了一种令人兴奋的新药候选药物SQ 641。SQ 641的活性上级于异烟肼（INH）和所有其他结核病药物，在适当的条件下，可迅速减少我们两种最佳结核病模型（巨噬细胞和小鼠）中的分枝杆菌。我们简要描述了药物的性质，包括其特殊的杀菌活性，其目标和作用机制（转位酶I），以及我们迄今为止开发口服制剂的努力。在本II期提案中，我们概述了确定用于口服治疗方案的商业上可行的SQ 641口服制剂以及有可能创建新治疗模式的胃肠外制剂的后续步骤;在诊断时给予单次胃肠外剂量。与目前的结核病护理标准相比，两种制剂和相关的治疗方案都将显著和快速地减少组织中的细菌，并大大缩短和改善结核病治疗时间。INH作为TB治疗的基础药物用于强化化疗的前2个月，因为其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。正如早期杀菌活性（EBA）临床研究所证明的那样，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SQ 641相比，INH是体外作用相对缓慢的药物，需要几天才能杀死MTB，并且具有仅17小时的抗生素后效应（PAE）。基于相对短的半衰期，每天施用该药物。尽管每日给药，但最近的研究表明，活菌数量仍足以促进生理性（Siddiqi et al. 2007）和基因型耐药菌。在暴露于INH 48小时后，约10%的MTB被杀死，但形态上仍然完整。相比之下，SQ 641在该时间范围内杀死90%的MTB，并且细菌被裂解（液体培养物是透明的）。此外，SQ 641的PAE为55小时，是INH PAE的3倍。防止耐药性的最佳方法是在细菌有机会适应药物之前迅速采取行动。SQ 641在体外可高效预防耐药突变体的产生，并与几种抗结核药（乙胺丁醇（EMB）、链霉素和新的Sequella药物SQ 109）具有显著的体外协同活性。SQ 641对耐药和耐药的MTB、M. kansasii，M. Acuessus和M.鸟，也可以开发用于非结核分支杆菌（NTM）疾病。尽管SQ 641对分枝杆菌具有显着的抗生素特性，但输送该药物的实用方法仍然是一个挑战。我们发现SQ 641激活巨噬细胞中的P-糖蛋白（P-gp）药物外排泵，因此在感染哺乳动物中携带MTB的这些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SQ 641对细胞内MTB的活性; SQ 641与INH（该试验系统中最有效的单一药物）相当或更好。在小鼠中，口服SQ 641吸收不良。出于多种原因（患者可接受性、方便性和成本），口服给药是TB治疗的首选方法。低生物利用度加上从巨噬细胞的快速流出意味着创造性地思考药物输送。幸运的是，我们通过将SQ 641与TPGS组合解决了外排和不溶性问题，TPGS是一种维生素E类似物，通常用于改善药物溶解度，从而提高生物利用度（EASTMAN and Company 2005）。稳定，4-6？构建了含有SQ 641（约分枝杆菌的大小）的TPGS颗粒。这些颗粒容易被巨噬细胞吞噬，并且SQ 641在吞噬体内释放，以高效且有效地杀死细胞内的MTB。在TB的巨噬细胞和小鼠模型中，SQ 641/TPGS制剂与INH一样有效。在本II期提案中，我们将评估各种方法（化学修饰以增强溶解度，改变药物-P-gp相互作用，并开发适当的商业递送系统）以溶解SQ 641并优化其体内递送。我们将探索配方，以确定这种有效的抗菌剂是否可以口服（与目前的标准治疗结核病药物联合使用或作为一种或多种这些药物的替代品）和/或应该胃肠外给药，以启动结核病化疗，并在结核病治疗的强化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.