Development of Multispecific Antibodies for the treatment of Methicillin Resistant Staphylococcus ‎aureus (MRSA) infection

摘要 通过这个项目，我们建议开发针对金黄色葡萄球菌（S.a.）的 同时靶向多种分泌型S.a.毒素，以及细胞表面的目标，在一个分子，也 含有功能性人IgG 1 Fc结构域。S.金黄色葡萄球菌感染非常常见，其治疗方法是 由于抗生素耐药性的扩大而变得更加复杂。Inhibrx开发了一个平台， 多个骆驼科动物仅重链可变结构域（VHH）与Fc效应子一起端对端连接 结构域，以任何顺序产生多价、多特异性分子，靶向单个表位上的多个表位。 目标或多个目标。我们已经开发了四价、双特异性仅重链抗体， 对5种S.a.毒素我们建议将这种抗体与细菌表面结合物联合收割机结合， 组分以产生多特异性抗MRSA抗体。我们假设毒素阻断功能将 保护募集到感染部位的免疫细胞，而细胞结合能力将使 S.A.，我们靶向了两个高度保守的S.a.细胞表面蛋白 抗体的开发：蛋白A和ERFB，并确定了一些候选的高亲和力抗体 针对这些目标中的任何一个。重要的是，由于蛋白A在非免疫性免疫应答中结合抗体的Fc区， 为了防止细菌的有效调理作用，Inhibrx整合了一个专有的Fc结构域， 不会将蛋白A结合到我们的抗蛋白A靶向抗体中，产生抗体，避免非- 免疫蛋白A结合。在本申请中，我们提出从以下选择细菌结合抗体： 在上述候选人中，并使用它们来创建六价多特异性抗体， 毒素阻断VHH靶向5个S.a.毒素、细胞表面结合VHH和蛋白A 抗Fc结构域，所有在一个抗体治疗。 作为用于我们的候选治疗剂的VHH所取自的组分抗体， 起源，我们在具体目标#1中提出利用Inhibrx的人源化免疫策略来使抗体相容 人类管理。在特定目标#2中，我们的先导细胞靶向抗体将在以下条件下进行结合比较： 为了选择一种或两种的先导抗体， 用于开发多特异性抗体的靶标。最后，在具体目标#3中，人源化铅毒素 阻断抗体和在特异性目标#2中选择的人源化EFB-和蛋白A-结合抗体将 使用Inhibrx平台以各种形式组合。将根据以下因素选择先导治疗抗体： 毒素阻断和细菌结合能力。然后将在体外功能性试验中测试多特异性抗体。 研究以及S.a.感染在第一阶段结束时，我们将准备 申请II期资助，在NHP中进行PK和IND研究，之后Inhibrx将获得 证明了无与伦比的抗MRSA治疗的临床前疗效。

Abstract Through this project we propose to develop a therapeutic antibody against Staphylococcus aureus (S.a.) that simultaneously targets multiple secreted S.a. toxins, as well as a cell-surface target, in a molecule that also contains a functional human IgG1 Fc domain. S. aureus infections are very common and their treatment is becoming more complex due to broadening antibiotic resistance. Inhibrx has developed a platform where multiple camelid heavy chain only variable domains (VHHs) are joined end to end, together with an Fc effector domain, in any order to produce multi-valent, multi-specific molecules targeting multiple epitopes on a single target or multiple targets. We have already developed a tetravalent, bispecific heavy chain only antibody, with specificity against five S.a. toxins. We propose to combine this antibody with a bacterial surface binding component to create a multi-specific anti-‎MRSA antibody. We hypothesize that toxin blocking functionality will protect immune cells recruited to the site of infection, while cell binding capability will enable opsonization of S.a., followed by its clearance.‎ We have targeted two highly conserved S.a. cell surface proteins for development of antibodies: Protein A and ‎EFB, and identified a number of candidate high affinity antibodies against either of these targets. Importantly, as Protein A binds the Fc region of antibodies in a non-immune fashion, preventing efficient opsonization of the bacterium, Inhibrx has integrated a proprietary Fc domain that does not bind Protein A into our anti-Protein A targeting antibodies, producing antibodies that avoid non- immune Protein A binding. In the present application we propose to select bacterial binding antibodies from among the above candidates, and use them to create hexavalent, multi-specific antibodies that incorporate toxin blocking VHHs targeting five S.a. toxins, together with cell surface-binding VHHs, and a Protein A resistant Fc domain, all in one antibody therapeutic. As the component antibodies from which the VHHs for our candidate therapeutic are taken are camelid in origin, we propose in Specific Aim #1 to utilize‎Inhibrx’s‎humanization‎strategy to make the antibody compatible with human administration. In Specific Aim #2 our lead cell targeting antibodies will be compared for binding in the presence of their natural substrates and to whole bacteria in order to select lead antibodies for one or both targets for development of multi-specific antibody. Finally, in Specific Aim #3, the humanized lead toxin blocking antibodies and the humanized EFB- and Protein A-binding antibodies selected in Specific Aim #2, will be combined in various formats using the Inhibrx platform. A lead therapeutic antibody will be chosen based on toxin blocking and bacterial binding capabilities. Multi-specific antibodies will then be tested in in vitro functional studies as well as in vivo (murine) models of S.a. infection. At the conclusion of Phase I, we will be ready to apply for Phase II funding to perform PK and IND enabling studies in NHPs, after which point Inhibrx will have demonstrated pre-clinical efficacy of an unparalleled anti-MRSA therapeutic.