Clinical Translation of a Neuron Protective Recombinant Human Antibody

描述（由申请人提供）：目前没有有效的治疗方法来预防或逆转ms的神经功能缺陷，所有可用的药物都针对免疫系统。长期的中枢神经系统修复可能需要转变思维模式，将重点放在针对神经系统的药物上。我们已经鉴定出一种人类单克隆IgM，它可以结合到活神经元的表面，包括那些来自人类的神经元。IgM促进神经突延伸，甚至在正常抑制性中枢神经系统髓磷脂存在的情况下，保护培养的神经元免于细胞死亡。IgM是从一个人的血清中分离出来的，这个人多年来一直高水平携带IgM，没有出现不良反应，也没有显示出对细胞或动物有毒性的迹象。在体内，IgM改善了病毒（Theiler小鼠脑脊髓炎病毒，TMEV）介导的慢性进行性多发性硬化症小鼠模型的脊髓轴突健康，构建了IgM的重组形式，称为rHIgM12，建立了研究生产细胞系，获得了GMP生产认证，并储存在供应商处。我们使用适合GLP和GMP生产的程序制造和纯化了超过200毫克的rHIgM12。单次静脉注射rHIgM12 （25 mg/kg）的效果已被证明可以保护TMEV ms模型中的轴突和神经功能缺陷。在功能改善的时间框架内，脊髓中有髓鞘的轴突数量得以保留，脑干中n -乙酰天冬氨酸（NAA）浓度增加。我们已经证实在脑干中使用NAA作为整个脊髓轴突保存的替代标记（37）。这种基于MRS的分析很容易适用于人类研究，可能成为一个有效的临床试验终点。外周给药后，rHIgM12在脊髓病变内积累，与轴突标记物，神经丝共定位。我们的数据支持IgM通过与神经节苷类结合，激活微管蛋白并启动导致轴突保护和过程扩展的信号来聚集神经元膜结构域的作用机制。该项目旨在为rHIgM12生成足够的安全性和剂量反应数据，以支持更大的转化项目。1)自身免疫介导的多发性硬化症（EAE）模型的疗效和安全性研究将解决在主动自身免疫情况下给予中枢神经系统结合的Ab可能加剧疾病的担忧。2) TMEV模型对轴突有明显的保护作用。在该模型中进行严格的剂量反应研究将进一步确定最小有效剂量并指导安全性研究。3)测量rHIgM12穿过血脑屏障能力的研究将加强支持中枢神经系统内直接信号传导的数据，使用rHIgM12的跨物种组织结合研究将为安全性研究中的物种选择提供依据。

DESCRIPTION (provided by applicant): There are currently no effective treatments to prevent or reverse neurologic deficits in MS. All available drugs target the immune system. Long term CNS repair may require a paradigm shift to focus on drugs that target the nervous system. We have identified a human monoclonal IgM that binds to the surface of living neurons, including those of human origin. The IgM promotes neurite extension even in the presence of normally inhibitory CNS myelin and protects neurons in culture from cell death. The IgM was isolated from the serum of an individual who carried it at high levels for many years without adverse effects and has shown no signs of toxicity to cells or animals. In vivo the IgM improves spinal cord axon health in a virus (Theiler's murine encephalomyelitis virus, TMEV) mediated mouse model of chronic progressive MS. A recombinant form of the IgM, called rHIgM12, was constructed, a research production cell line established, certified for GMP production and banked at a vendor. We have manufactured and purified over 200 mg of rHIgM12 using a procedure appropriate for GLP and GMP production. The efficacy of a single i.v. dose of rHIgM12 (25 mg/kg) has been demonstrated to protect axons and preserve neurologic deficits in the TMEV model of MS. Over the time frame of functional improvement, the number of myelinated axons in the spinal cord are preserved, and N-acetyl aspartate (NAA) concentrations in the brain stem increase, as measured by magnetic resonance spectroscopy (MRS). We have validated the use of NAA in the brain stem as a surrogate marker of axon preservation throughout the spinal cord (37). This MRS based assay is easily applicable to human studies and may become a valid clinical trial endpoint. After peripheral administration rHIgM12 accumulates within spinal cord lesions, co-localized with the axon marker, neurofilament. Our data supports a mechanism of action in which the IgM clusters neuron membrane domains by binding to gangliosides, activating tubulin and initiating signals that result in axon protection and process extension. This project is designed to generate sufficient safety and dose response data for rHIgM12 to support a larger translational program. 1) Efficacy and safety studies in an autoimmune mediated model of MS (EAE) will address concerns that administering a CNS binding Ab in the face of active autoimmunity may exacerbate disease. 2) There is clear efficacy in protecting axons in the TMEV model. A rigorous dose response study in this model will further define the minimum effective dose and guide safety studies. 3) Studies to measure the ability of rHIgM12 to cross the blood brain barrier will strengthen the data supporting direct signaling within the CNS and tissue binding studies across species using rHIgM12 will justify species selection in safety studies.