Monoclonal antibodies targeting novel sites of vulnerability in marburg virus glycoprotein

丝状病毒，由埃博拉病毒和马尔堡病毒(Marv和MarburgVirus)两个主要病毒家族组成 RAVV)引起周期性的严重病毒性出血热暴发，死亡率高达90%。因为它 很难预测哪些物种会主导未来的疫情，发展具有广泛的保护性 预防和管理未来丝状病毒暴发的治疗是高度优先的。与最近形成鲜明对比的是 我们和其他人报告的重大突破是关于隔离和发展一些有效和广泛的 针对埃博拉病毒的中和单抗(BNAbs)，只有一类抗MarburgVirus GP的单抗被 描述了以MarV和RAVV gp的受体结合位点(RBS)内的相同表位为靶点。MR191 是唯一一种MARV/RAVV gP RBS特异性单抗(MAb)，已被证明可预防 然而，在非人类灵长类动物(NHP)中，MARV感染的剂量非常高(两次剂量各为50 mg/kg)。因此，它 对于识别Marv/RAVV GP中新的漏洞位置并开发更有效的 针对这些致命病毒的免疫疗法。拥有各种各样的bNAbs将允许设计治疗 含有多个针对不同表位的单抗的鸡尾酒，这一策略已被证明是非常 有效对抗埃博拉病毒，以对抗可能的病毒逃逸变体。 综合生物治疗公司(IBT)和 马里兰大学(UMD)最近发现了高度有效的埃博拉病毒bNAbs，具有显著的 EBOV、SUDV和BDBV动物模型包括非人灵长类动物模型和雪貂模型的有效性 感染(赵等人，细胞169,891-904 e815(2017))。最近，在卫生保健计划中使用了优质/强化免疫策略 结合一种新的带有工程gp突变体的记忆B细胞反筛选，我们能够分离出， 第一次，一组高度有效的MARV/RAVV bNAb靶向于一类不同于 与苏格兰皇家银行绑定的MR系列。在这项STTR应用中，我们的目标是解决Marv 通过开发源自这些新的主要候选MarburgVirus的治疗性抗体进行免疫治疗 MARV/RAVV bNAbs。我们将i)从当前的bNAb候选中选择3-4个先导治疗性单抗；ii)优化 通过最先进的计算机辅助，领导mAbs并选择最终的人性化/优化候选人 在严格的豚鼠MARV感染模型中的优化和有效性研究；以及iii)确定最终的导联 通过检测MAb(或鸡尾酒)候选在NHP模型中感染MARV的疗效。在完成 拟议的第一阶段项目我们设想了第二阶段项目，目标如下：一)扩大疗效 NHP中RAVV和剂量优化的研究；II)建立CHO细胞制造细胞系，III)发展 产品释放和PK的生物分析方法，以及iv)使用以下方法进行安全性和组织交叉反应研究 GLP级临床候选人。如果成功，我们预计该产品将在国防部或 BARDA根据FDA动物规则提供资金并获得批准。

Filoviruses, consisting of two major virus families including the ebolaviruses and marburgviruses (MARV and RAVV), cause periodic outbreaks of severe viral hemorrhagic fever with mortality rates as high as 90%. Since it is difficult to predict the species that would dominate future outbreaks, development of broadly protective therapeutics to prevent and manage future filovirus outbreaks is of high priority. In sharp contrast to the recent major breakthrough reported by us and others on isolation and development of a number of effective and broadly neutralizing mAbs (bNAbs) for ebolaviruses, only a single class of mAbs against marburgvirus GP has been described that target the same epitope within the receptor binding site (RBS) of MARV and RAVV GP. MR191 is the only MARV/RAVV GP RBS-specific monoclonal antibody (mAb) that has been shown to protect against MARV infection in nonhuman primates (NHPs) however at very high doses (2 doses of 50 mg/kg each). Thus, it is important to identify novel sites of vulnerability in MARV/RAVV GP and develop more potent immunotherapeutics against these deadly viruses. Having a variety of bNAbs will allow the design of therapeutic cocktails containing multiple mAbs targeting distinct epitopes, a strategy that has been shown tobe extremely effective against ebolaviruses to combat possible virus escape variants. There has been a long-standing and productive collaboration between Integrated BioTherapeutics (IBT) and University of Maryland (UMD) that has recently resulted in highly potent ebolavirus bNAbs with remarkable efficacy in animal models including nonhuman primate (NHP) and ferret models of EBOV, SUDV, and BDBV infection (Zhao et al., Cell 169, 891-904 e815 (2017)). Lately, using a prime/boost immunization strategy in NHPs combined with a novel memory B cell counter-screening with engineered GP mutants, we were able to isolate, for the first time, a group of highly potent MARV/RAVV bNAbs that target a new class of epitopes distinct from the RBS-binding MR series. In this STTR application, we aim to address the major challenge of MARV immunotherapy by developing top lead candidate marburgvirus therapeutic antibodies derived from these novel MARV/RAVV bNAbs. We will i) select 3-4 lead therapeutic mAbs among the current bNAb candidates; ii) optimize the lead mAbs and select for the final humanized/optimized candidate by state-of-the-art computer-aided optimization and efficacy study in a stringent guinea pig model of MARV infection; and iii) identify the final lead mAb (or cocktail) by testing the efficacy of candidates in NHP model of MARV infection. Upon completion of the proposed Phase I project we envision a Phase II project with the following objectives: i) expand the efficacy studies to RAVV and dose optimization in NHPs; ii) develop manufacturing cell lines in CHO cells, iii) develop bioanalytical methods for product release and PK, and iv) conduct safety and tissue cross reactivity studies using the GLP-grade clinical candidate. If successful, we anticipate further development of the product under DoD or BARDA funding and approval under FDA Animal Rule.