Clinical Translation of a Neuron Protective Recombinant Human Antibody

描述(申请人提供)：目前还没有有效的治疗方法来预防或逆转多发性硬化症的神经功能障碍。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范式转变，将重点放在针对神经系统的药物上。我们已经鉴定出一种与活神经元表面结合的人类单抗IgM，包括人类来源的神经元。即使在正常抑制的中枢神经系统髓鞘存在的情况下，IgM也能促进轴突延伸，并保护培养中的神经元免受细胞死亡的影响。免疫球蛋白M是从一名多年来携带高水平免疫球蛋白的人的血清中分离出来的，没有不良反应，也没有显示出对细胞或动物的毒性迹象。在体内，在一种病毒(泰勒氏小鼠脑脊髓炎病毒，TMEV)介导的慢性进行性MS小鼠模型中，IgM改善了脊髓轴突的健康。构建了一种称为rHIgM12的IgM重组形式，建立了研究生产细胞系，获得了生产GMP的认证，并储存在供应商处。我们已经使用适合于GLP和GMP生产的程序生产和纯化了超过200毫克的rHIgM12。单次静脉注射的疗效。在多发性硬化的TMEV模型中，剂量为25 mg/kg的rHIgM12已被证明具有保护轴突和保护神经功能缺失的作用。在功能改善的时间框架内，通过磁共振波谱(MRS)测量，脊髓中有髓轴突的数量被保留，而脑干中N-乙酰天冬氨酸(NAA)的浓度增加。我们验证了脑干NAA作为整个脊髓轴突保留的替代标记物的使用(37)。这种基于MRS的分析很容易应用于人体研究，并可能成为有效的临床试验终点。外周给药后，rHIgM12在脊髓损伤处蓄积，并与轴突标志物神经丝共同定位。我们的数据支持一种作用机制，即IgM通过与神经节苷脂结合、激活微管蛋白并启动导致轴突保护和突起延伸的信号来聚集神经元膜域。该项目旨在为rHIgM12生成足够的安全性和剂量响应数据，以支持更大的翻译计划。1)在自身免疫介导的多发性硬化(EAE)模型中的有效性和安全性研究将解决人们的担忧，即面对主动的自身免疫，给予中枢神经系统结合抗体可能会加剧疾病。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跨越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递的数据，使用rHIgM12进行的跨物种组织结合研究将证明安全性研究中的物种选择是合理的。

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.