Inhaled tigecycline therapy for pulmonary M. abscessus infections

摘要 脓肿分枝杆菌(MAB)是一种引起慢性肺部感染的非结核分枝杆菌。 (PMAb)和既有肺部疾病的患者(尤其是囊性纤维化患者)容易发生 PMAB。由于MAB固有的抗生素耐药性，治疗往往复杂且治愈率低。 替加环素是一种甘环素类抗生素，对pMAb有杀菌作用，但不诱导 细菌耐药机制。对于pMAb治疗，患者每天接受两次静脉注射 在至少一个月内服用替加环素会导致严重的副作用，许多患者退出 治疗。替格环素有可能成为pMAb和pMAB治疗的一线药物 新联合疗法的主心骨，但要充分发挥其治疗潜力，我们需要改进 替加环素类药物疗效与安全性/耐受性的比率，即其治疗指数。解决这个问题的一种方法 面临的挑战是开发易于管理且效果良好的替吉环素吸入性制剂 被容忍了。在初步研究中，用pMAb感染的GM-CSF KO小鼠被肺内雾化吸入 替加环素28天。治疗满疗程后的肺部细菌负荷显示吸入 替格环素的疗效高，且具有剂量依赖性，且耐受性良好。在这里我们假设气雾剂的传递 替加环素是治疗pMAB的一种可行的方法。在目标1中，为了避免对替吉环素的要求 重组，我们将开发一种具有良好空气动力学特性的替加环素干粉配方 适合吸入的特性。目标2将研究剂量、给药方案和结果之间的关系 替加环素气雾剂在不同体液、器官和组织中的暴露。我们会特别研究 替吉环素吸入与静脉给药的剂量-暴露关系及其在血浆、肺中的利用度 脓肿和上皮性衬里液体。在目标3中，我们建议测试疗效、剂量、给药频率和 吸入替吉环素抗pMAb动物模型的持续时间。我们建议首先使用GM-CSF KO 小鼠模型，随后，我们将在pMAb感染的b-enac转基因小鼠中测试最佳方案，作为 囊性纤维化患者的代表性模型。最佳方案将在感染选定病毒的小鼠身上得到验证 单抗克隆1和2的临床分离株以及囊性纤维化患者的分离株。目标4将 确定吸入替吉环素在多药治疗中的疗效。与Aim 3中相同的pMAb小鼠(带品系 #21或临床分离株)将使用吸入替吉环素和 克拉霉素(口服)、氯法齐明(口服)、贝达奎兰(口服)。这些研究将由一个财团进行 科罗拉多州立大学、田纳西大学、三角研究所和国立大学的专家 犹太医院。通过合作，我们的目标是提供一种替环素吸入疗法，该疗法具有良好的 明确的空气动力学和PK特性，以及对未来临床前毒理学的体内疗效的良好表征 在更大的动物模型中的研究，IND的应用，以及最终对患者的管理。

Summary Mycobacterium abscessus (MAB) is a nontuberculous mycobacterium that causes chronic pulmonary infections (pMAB) and patients with pre-existing lung disease (especially cystic fibrosis patients) have a predisposition to pMAB. Due to MAB’s intrinsic antibiotic resistance, treatment is often complex and with low cure rates. Tigecycline, a glycylcycline class antibiotic, demonstrates bactericidal effects against pMAB without eliciting bacterial resistance mechanisms. For pMAB treatment, patients receive twice daily intravenous administration of tigecycline during at least one month resulting in significant side effects and many patients withdraw from treatment. Tigecycline has the potential to qualify as the first-line agent during therapy for pMAB and the backbone for new combination regimens but to achieve its fullest therapeutic potential, we need to improve tigecyclines ratio between efficacy and safety/tolerability, i.e. its therapeutic index. One approach to address this challenge is to develop inhalational formulations of tigecycline that are easy to administer and are well tolerated. In preliminary studies, GM-CSF KO mice with pMAB were treated by intrapulmonary aerosols of tigecycline for 28 days. The pulmonary bacterial burden after full treatment duration showed that inhaled tigecycline has high, dose-dependent efficacy, and is well tolerated. Here we hypothesize that aerosol delivery of tigecycline is a viable therapeutic approach for pMAB. In Aim 1, to avoid the tigecycline requirements for reconstitution, we will develop a dry powder formulation of tigecycline with well characterized aerodynamic properties suitable for inhalation. Aim 2 will study the relationship between dose, dosing regimen and resulting exposure of aerosols of tigecycline in different body fluids, organs and tissues. In particular, we will study the dose-exposure relationship of inhaled versus intravenous tigecycline and its availability in plasma, lung, abscesses and epithelial lining fluid. In Aim 3, we propose to test the efficacy, dose, dosing frequency, and duration of inhaled tigecycline against pMAB using animal models. We propose using first the GM-CSF KO murine model, subsequently, we will test the best regimen in b-ENac Tg mice with pMAB infection, as a representative model for cystic fibrosis patients. The best regimen will be validated in mice infected with selected clinical isolates from MAB clones 1 and 2 and isolates obtained from cystic fibrosis patients. Aim 4 will determine efficacy of inhaled tigecycline in multidrug therapies. Mice with pMAB as in Aim 3 (with strain #21 or clinical isolates) will be treated with binary or ternary combinations of inhaled tigecycline and clarithromycin (oral), clofazimine (oral), bedaquiline (oral). These studies will be performed by a consortium of experts located at Colorado State University, University of Tennessee, Research Triangle Institute and National Jewish Hospital. Working together, we aim to provide an inhalational therapy regimen of tigecycline with well- defined aerodynamic and PK properties and well characterized in vivo efficacy for future preclinical toxicology studies in larger animal models, IND application, and ultimately administration to patients.