Infection Site Targeted Antitoxin Antibody (ISTAb) against Bacillus anthracis

针对炭疽杆菌的感染部位靶向抗毒素抗体 (ISTAb)

• 批准号: 10817474
• 负责人: Rajan P Adhikari
• 金额: $ 31.5万
• 依托单位: ABVACC, INC.
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-02-15 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10817474
• 关键词: Infection; Site; Targeted; Antitoxin; Antibody

Project Summary Bacillus anthracis (Ba) is a Gram-positive spore forming bacterium that is listed as an agent of highest concern (Category A) by NIAID and CDC. Ba is easy to grow, and its spores can be formulated into highly stable powder form and disseminated as aerosol or used to contaminate food or water. In 2001, letters laced with powdered anthrax spores were mailed to several US politicians. Twenty-two people, including 12 mail handlers, were infected, and five of them died. B. anthracis virulence largely depends on two key toxins generated by combination of the protective antigen (PA) associated with either lethal factor (LF) or edema factor (EF). Although some oral antibiotics and a vaccine are available for use, in practice these treatments cannot adequately address the adverse effects of bacterial toxins released post exposure. In our recently completed R41 project, we developed and tested a novel approach to target neutralizing anti-PA antibodies specifically to the site of infection in vitro and in vivo. The approach exploits the cell wall targeting domains (CWT) of well characterized phage endolysins (PlyG, PlyL and PlyB) that bind with species-specificity and high affinity to cell wall components of Ba. These CWTs are fused to specific antitoxin neutralizing monoclonal antibodies (mAbs) to generate Infection Site Targeted Antitoxin antibodies (ISTAbs). ISTAb technology provides two therapeutic advantages: immediate toxin neutralization at the site of infection preventing toxemia, and opsonophagocytic killing by phagocytes to simultaneously clear both bacteria and toxin. We compared nine ISTAb candidates (three CWTs and three mAbs) based on in vitro assays (cell binding and toxin neutralization) and selected one ISTAb (AVP-21D9-PlyG) for pre- and post-challenge in vivo studies in mice. This ISTAb exhibited significantly higher level of protection than the parental IgG. This R42 is aimed to take this lead ISTAb molecule into the next level in therapeutic pipeline. In this proposal, we will produce and extensively characterize next-generation AVP-21D9-PlyG ISTAbs, including stability and in vivo efficacy studies in mice and nonhuman primates (NHP), and develop a stable formulation. In Aim 1, we will use computer-aided optimizations to generate 3-5 ISTAb variants to remove potential liabilities that may complicate downstream development. In Aim 2, two lead candidates will be tested in mouse models. One lead molecule will be tested in an NHP model for PK and post-challenge efficacy. In Aim 3: The final ISTAb will be subjected to accelerated stability and PK studies, formulation, and generation of stable cell lines in CHO-S cells. The combination of immediate toxin clearance, phagocytic killing, and concurrent use of antibiotics, is expected to create synergy and yield a treatment that is far superior to the current standard of care. Furthermore, this technology can be applied to a variety of other bacterial pathogens where toxins play a key role in pathogenesis. Overall, this approach has board application as a platform technology across multiple pathogens.

项目概要 炭疽芽孢杆菌 (Ba) 是一种革兰氏阳性芽孢形成细菌，被列为最高致病菌。 NIAID 和 CDC 关注（A 类）。 Ba易于生长，其孢子可配制为高度 稳定的粉末形式并以气溶胶形式传播或用于污染食物或水。 2001年，字母系在一起 含有炭疽孢子粉的邮件被邮寄给几位美国政客。 22人，其中12封邮件 处理人员被感染，其中五人死亡。 B. 炭疽病毒力很大程度上取决于两种关键毒素 由与致死因子 (LF) 或水肿相关的保护性抗原 (PA) 组合产生 因子（EF）。尽管可以使用一些口服抗生素和疫苗，但实际上这些治疗方法 不能充分解决接触后释放的细菌毒素的不利影响。在我们最近 完成 R41 项目，我们开发并测试了一种靶向中和抗 PA 抗体的新方法 特别针对体外和体内的感染部位。该方法利用细胞壁靶向域 (CWT) 已充分表征的噬菌体内溶素（PlyG、PlyL 和 PlyB），它们与物种特异性结合并 与 Ba 细胞壁成分具有高亲和力。这些 CWT 与特定的抗毒素中和融合 单克隆抗体 (mAb) 产生感染部位靶向抗毒素抗体 (ISTAb)。 IST抗体 技术提供了两个治疗优势： 立即中和感染部位的毒素 预防毒血症，以及吞噬细胞的调理吞噬杀伤作用，同时清除细菌和 毒素。我们根据体外测定（细胞）比较了九种 ISTAb 候选药物（三种 CWT 和三种 mAb） 结合和毒素中和），并选择一种 ISTAb (AVP-21D9-PlyG) 用于攻击前和攻击后 小鼠体内研究。该 ISTAb 表现出比亲本 IgG 显着更高的保护水平。这 R42 旨在将这种领先的 ISTAb 分子带入治疗管道的新水平。在这个提案中， 我们将生产并广泛表征下一代 AVP-21D9-PlyG ISTAb，包括稳定性 以及小鼠和非人类灵长类动物 (NHP) 的体内功效研究，并开发出稳定的制剂。在 目标 1，我们将使用计算机辅助优化生成 3-5 个 ISTAb 变体，以消除潜在的 可能使下游发展复杂化的负债。在目标 2 中，两名主要候选人将接受测试 鼠标模型。将在 NHP 模型中测试一种先导分子的 PK 和攻击后功效。在 目标 3：最终的 ISTAb 将接受加速稳定性和 PK 研究、配制和生成 CHO-S 细胞中的稳定细胞系。立即清除毒素、吞噬细胞杀灭和 同时使用抗生素，有望产生协同作用并产生远远优于抗生素的治疗方法 目前的护理标准。此外，该技术还可应用于多种其他细菌 毒素在发病机制中起关键作用的病原体。总的来说，这种方法在电路板应用中是一种 跨多种病原体的平台技术。