A Novel Antibody that Promotes Neuronal Integrity and Neurogenesis for Treating Alzheimer's Disease

项目摘要 我们的目标是开发一种新的神经元穿透双特异性抗体，促进神经元的完整性， 用于治疗AD的神经发生。仅在美国，目前就有超过600万美国人患有AD， 到2021年，总经济成本约为3550亿美元。尽管成本惊人，只有少数温和有效 存在治疗AD的药物。因此，治疗甚至逆转AD的影响仍然是一个挑战。 未满足的重大需求。 在病理学上，AD的特征是大脑中存在神经炎斑块和神经原纤维缠结。 细胞外神经炎斑块的主要成分是β-淀粉样蛋白（Aβ），约占4% kDa片段蛋白水解衍生自较大的淀粉样前体蛋白（APP）2。大量的 文献表明Aβ蓄积是AD进展的中心， 生产代表了治疗AD的有希望的策略。 我们已经产生了两个单链可变区抗体片段（scFv），Asec和Bsec， 分别促进α-分泌酶活性和阻断β-分泌酶活性 (APP)通过在α位点或β位点与APP结合3 -5。接下来，我们产生了串联双特异性抗体， 结合了Asec和Bsec scFv，并显示它提高了sAPPα的水平，sAPP α是一种可溶性α-分泌酶， 相关APP片段，并降低Aβ和sAPPβ（可溶性β分泌酶相关片段）的水平 在AD 6的细胞模型中。将ApoB标签添加到双特异性抗体（称为VTC-939），其可以促进免疫原性。 通过血脑屏障（BBB）6-8的转移和神经元靶向。使用重组人腺病毒， VTC-939作为感染肝细胞的载体，可分泌到血液中， 大脑处于高水平。当在APP/PS1 AD小鼠模型中测试VTC-939作为治疗剂时， sAPPα水平升高，而Aβ沉积和寡聚体Aβ水平降低。此外，VTC-939 治疗增加了神经元健康，显著增加了海马神经发生， 与未处理小鼠相比，存活率增加9.这些结果表明，改变APP处理， 抑制毒性淀粉样蛋白生成β位点活性，同时促进神经保护性α-分泌酶 加工提供了增加的神经元益处，并且代表了一种有前途的新的治疗方法， 治疗并可能逆转AD。 基于这项工作，我们的目标是开发VTC-939作为一种新型的神经元穿透抗体， 恢复神经元的完整性并促进神经发生，用于治疗AD。具体目标是：1） 产生抗体构建体并建立质量控制测定，2）确定 VTC-939促进APP/PS1 AD小鼠模型中的神经元完整性、神经发生和寿命，以及3） 产生VTC-939在正常健康小鼠中的急性毒理学和生物分布概况。一种可以 安全有效地促进神经元的完整性和神经发生将提供显著的进步， 明确的未满足的医疗需求。

Project Summary Our goal is to develop a novel neuron-penetrating bispecific antibody that promotes neuronal integrity and neurogenesis for the treatment of AD. In the US alone, over 6 million Americans are currently living with AD, with total economic costs around $355 billion in 20211. Despite the staggering cost, only a few mildly effective AD symptom-treating drugs exist. As a result, treating and even reversing the effects of AD remains a significant unmet need. Pathologically, AD is characterized by the presence of neuritic plaques and neurofibrillary tangles in the brain. The primary component of the extracellular neuritic plaques is the β-amyloid protein (Aβ), an approximately 4 kDa fragment proteolytically derived from the larger amyloid precursor protein (APP)2. A vast amount of literature has implicated Aβ accumulation as being central to the progression of AD, and inhibiting Aβ production represents a promising strategy for treating AD. We have generated two single-chain variable domain antibody fragments (scFv), Asec and Bsec, which respectively promote α-secretase activity and block β-secretase activity toward amyloid precursor protein (APP) by binding to APP at either the α-site or the β-site3-5. Next, we generated a tandem bispecific antibody that combines the Asec and Bsec scFvs and showed that it elevates levels of sAPPα, a soluble α-secretase- associated APP fragment, and decreases levels of Aβ and sAPPβ, a soluble β-secretase-associated fragment in cell models of AD6. An ApoB tag was added to the bispecific antibody (called VTC-939), which can facilitate transfer across the blood-brain barrier (BBB)6-8 and neuronal targeting. Using recombinant human adeno- associated virus (rAAV) as a vector infective to hepatic cells, VTC-939 could be secreted into the blood and brain at high levels. When VTC-939 was tested as a therapeutic in an APP/PS1 AD mouse model, VTC-939 increased levels of sAPPα, while decreasing Aβ deposits and oligomeric Aβ levels. In addition, VTC-939 treatment increased neuronal health, substantially increased hippocampal neurogenesis and significantly increased survival rates compared with untreated mice9. These results indicate that altering APP processing to inhibit toxic amyloidogenic β-site activity while simultaneously promoting neuroprotective α-secretase processing provides increased neuronal benefits and represents a promising new therapeutic approach for treating, and potentially reversing AD. Building from this work, our objective is to develop VTC-939 as a novel neuron-penetrating antibody that restores neuronal integrity and promotes neurogenesis for the treatment of AD. The specific aims are to: 1) produce antibody constructs and establish quality control assays, 2) determine the optimal effective dose of VTC-939 to promote neuronal integrity, neurogenesis and longevity in the APP/PS1 AD mouse model, and 3) generate acute toxicology and biodistribution profiles for VTC-939 in normal healthy mice. A therapy that can safely and effectively promote neuronal integrity and neurogenesis would provide a significant advancement for a clear unmet medical need.