Temporal Biomarker-Powered Immunotherapy Targeting GFAP for Traumatic Brain Injury

摘要 创伤性脑损伤（TBI）是美国死亡率和发病率的主要原因， 每年有超过200万新患者，并且没有FDA批准的治疗方法。TBI 诱导早期高浓度的细胞毒性谷氨酸波进入突触， 超过了星形胶质细胞谷氨酸转运蛋白（如GLT-1）的缓冲能力， 脑细胞的损伤和死亡。在这种神经损伤的情况下，钙蛋白酶- 产生，38 kDa的神经胶质细胞酸性蛋白（GBDP）的核心分解产物， 在损伤后数小时至数天内从损伤的星形胶质细胞释放。与此同时，其他 蛋白质“碎片”从神经元细胞体释放（泛素C末端水解酶1 /UCH-L1）和损伤的轴突（神经毒性重/pNF-H和轻/NF-L，Tau和 磷酸化的Tau /p-Tau）。事实上，我们最新的TRACK-TBI临床数据和 CENTER-TBI多中心联盟研究表明，GFAP/GDBPs是最常见的 TBI后大量蛋白质碎片释放到循环中。重要的是，我们和 另一些人发现，GBDP易于形成具有神经毒性的蛋白质聚集体， 外化的时候。Grus及其同事报道，抗GFAP抗体 对培养的神经视网膜细胞和视网膜神经节细胞的神经保护作用 胁迫下的器官型培养。同样，GBDP主动免疫也是 在TBI小鼠模型中的神经保护作用，包括GBDP水平的减弱， 减少TBI的关键神经病理学生物标志物， 神经功能结果。因此，我们的中心假设是， 用具有效应子能力的IgG单克隆抗体（mAb）进行免疫治疗， GBDP将加速大脑修复，改善认知和其他结果指标 在TBI患者中。我们提出的作用机制是有益的调理作用 抗GBDP mAb（IgG）的神经毒性GBDP碎片，然后加速 通过活化的FcγR+吞噬细胞的吞噬作用。我们的使用内容是TBI患者， 严重损伤，定义为初始GCS为6-12的中度至重度TBI患者 和升高的水平的选定的急性时间预测生物标志物， 招生我们建议的给药途径是静脉内多日输注 抗GBDP单克隆抗体以最大化脑暴露， 药效学（PD）生物标志物（如GBDP、NFL、Tau和p-Tau）来跟踪 治疗反应和调整剂量。在这个项目中，我们利用我们的协同效应， 专业知识，以测试我们的假设（第一阶段）的概念验证在体外和细胞为基础的 在（II期）体内剂量范围和疗效研究之前进行研究， 描述我们领先的抗GBDP mAb免疫治疗候选药物。我们的初步 临床前研究现在表明，损伤前，主动免疫GDBP和后， 抗GBDP单克隆抗体损伤被动免疫治疗在TBI中是安全和有益的 小鼠此外，我们展示了PD生物标志物如何用于跟踪治疗 反应和调整剂量，以便从实验室成功转化为临床 并帮助做出有意义的获益-风险决策。

ABSTRACT Traumatic brain injury (TBI) is a leading cause of mortality and morbidity in the US, with over two million new patients each year and no FDA-approved therapeutics. TBI induces an early, high concentration wave of cytotoxic glutamate into synapses that exceeds the buffering capacity of astroglial glutamate transporters (e.g. GLT-1), causing injury and death of brain cells. Under these neurotrauma conditions, the calpain- generated, 38 kDa core breakdown product of glial fibrillary acidic protein (GBDP) was released from injured astrocytes within hours to days post-injury. In parallel, other protein “debris” are released from neuronal cell bodies (ubiquitin C terminal hydrolase 1 /UCH-L1) and injured axons (neurofilament-heavy /pNF-H and light /NF-L, Tau and phosphorylated Tau /p-Tau). In fact, our most recent clinical data from TRACK-TBI and CENTER-TBI multicenter consortium studies showed that GFAP/GDBPs are the most the abundant protein debris released into the circulation after TBI. Significantly, we and others discovered that GBDPs are prone to form protein aggregates that are neurotoxic when externalized. Grus and coworkers reported that anti-GFAP antibodies have neuroprotective effects on cultured neuro-retinal cells and on retinal ganglion cells in organotypic culture under stress. Similarly, GBDP active immunization was neuroprotective in a mouse model of TBI, including attenuation of GBDP levels, reduction of key neuropathological biomarkers of TBI, and improvement of neurofunctional outcomes. Therefore, our central hypothesis is that passive immunotherapy with effector-competent IgG monoclonal antibodies (mAbs) against GBDP will accelerate brain repair and improve cognition and other outcome measures in TBI patients. Our proposed mechanism of action is the beneficial opsonization of neurotoxic GBDP debris by anti-GBDP mAb (IgG), followed by accelerated phagocytosis by activated FcγR+ phagocytes. Our content of use is TBI patients with a significant injury, as defined by moderate to severe TBI patients with initial GCS of 6-12 and elevated levels of selected acute temporal predictive biomarkers for targeted enrollment. Our proposed route of administration is intravenous multiday infusion of anti-GBDP mAbs to maximize brain exposure, with subacute temporal pharmacodynamic (PD) biomarkers (such as GBDP, NFL, Tau and p-Tau) to track treatment response and adjust dosing. In this project, we leverage our synergistic expertise to test our hypothesis with (Phase I) proof-of-concept in vitro and cell-based studies prior to (Phase II) in vivo dose-ranging and efficacy studies to prioritize and characterize our lead anti-GBDP mAb immunotherapy candidates. Our preliminary preclinical studies now show that pre-injury, active immunization with GDBP AND post- injury passive immunotherapy with anti-GBDP mAbs are safe and beneficial in TBI mice. Moreover, we show how PD biomarkers might be employed to track treatment response and adjust dosing for successful translation from the laboratory to the clinic and to aid in meaningful benefit–risk decision-making.