Chemokine Decoy Receptor for Therapy of Autoimmune Arthritis

描述（由申请方提供）：目前治疗类风湿性关节炎（“RA”）的方法（皮质类固醇、甲氨蝶呤、中和TNF-？）依赖于广谱免疫抑制，这种方法不是一致有效的，并且经常与显著的副作用相关。为了解决这一市场缺口，Radikal Therapeutics（RTX）正在开发一种新型可溶性受体诱饵受体融合蛋白（hR-421），可诱导抗原（Ag）特异性活化T细胞的免疫耐受。hR-421由Ig-Fc和CCR 5受体的第二胞外结构域构建，结合并中和所有3种CCR 5结合趋化因子配体（MIP-β，MIP-？，RANTES）并阻止它们与CCR 1、CCR 3和CCR 5膜受体的结合和激活。与CCR 5抑制剂相反，mR-421（hR-421的鼠同源物）阻断CCR 5非依赖性促炎通路，并且在CCR 5敲除小鼠中有效。使用mR- 421的治疗深刻地抑制了实验性过敏性脑脊髓炎（EAE），一种经典的自身免疫模型系统，即使在疾病发作后开始治疗。此外，从用mR-421在体内处理的EAE供体中分离的Ag特异性效应Th 1细胞产生显著更少的促炎细胞因子，并在过继转移实验中抑制EAE。后一种效应是由mR-421阻止Th 1 CD 4 + T细胞上的共刺激信号的能力驱动的。基于这些发现，我们假设R-421将阻止共刺激，从而阻止RA中Th 1 CD 4+细胞的下游增殖和活化。我们现在建议将R-421技术的保护作用扩展到已发表的神经炎症研究结果之外，并在临床相关的RA模型中建立其潜在益处。用CFA中的胶原蛋白接种并在第21天再次激发以诱导自身免疫性关节炎的雄性DBA小鼠将在显著疾病时（第21天）开始用mR-421（2、4、8 mg/kg）、不相关的IgG 1对照或依那西普（6.25 mg/kg）治疗，如关节炎评分2（0-16的量表）所表征的。此外，我们还将纳入一个未暴露于胶原蛋白/CFA或治疗的假手术对照组。将在6周的时间内监测动物的关节炎临床证据，在对照组中，该时间点的特征在于整个爪子（包括脚趾）的红斑和水肿（评分=12）。血浆m-R421浓度将与临床结局相关，以构建指导未来临床给药的药效学特征。我们预期mR-421以剂量和血浆浓度依赖性方式减少关节损伤，定义为平均关节炎评分的降低等同于或上级于金标准临床批准药物依那西普引起的治疗效果。预计这些发现与mR-421对滑膜脂质过氧化、中性粒细胞浸润、促炎基因表达过氧亚硝酸盐生成、聚（ADP-核糖）聚合酶形成、大体和组织学损伤评分以及对Th 1和Treg淋巴细胞引流淋巴结群的影响相似。 公共卫生相关性：风湿性关节炎是一种毁灭性的自身免疫性疾病，其特征是终身残疾和不可阻挡的进展。目前批准的药物是部分有效的，近三分之一的患者没有得到充分的缓解。我们正在开发一种新的药物，专门阻断这种情况下的特定免疫紊乱。我们将在临床相关的小动物模型中测试这种药物，并确定最有效的剂量，预计将进行确定性的大动物研究以确认其疗效。 和安全性

DESCRIPTION (provided by applicant): Current therapeutic approaches to rheumatoid arthritis ("RA") (corticosteroids, methotrexate, neutralization of TNF-?) rely upon broad-spectrum immunosuppression, an approach that is not uniformly effective and is frequently associated with significant side-effects. To address this market gap, Radikal Therapeutics (RTX) is developing a novel soluble receptor decoy receptor fusion protein (hR-421) that induces immune tolerance in antigen (Ag)-specific activated T-cells. Constructed from Ig-Fc and the second ecto domain of the CCR5 receptor, hR-421 binds and neutralizes al 3 CCR5-binding chemokine ligands (MIP-?, MIP-?, RANTES) and prevents their binding and activation of the CCR1, CCR3, and CCR5 membrane receptors. In contrast to CCR5 inhibitors, mR-421 (the murine homologue of hR-421) blocks CCR5-independent pro-inflammatory pathways and is effective in CCR5 knock-out mice. Therapy with mR- 421 profoundly suppresses experimental allergic encephalomyelitis (EAE), a classic autoimmune model system, even when treatment is initiated after disease onset. Moreover, Ag-specific effector Th1 cells isolated from EAE donors treated in vivo with mR-421 produce substantially less pro-inflammatory cytokines and suppress EAE in adoptive transfer experiments. This latter effect is driven by the ability of mR-421 to prevent the co-stimulatory signal on Th1 CD4+ T cells. Based on these findings, we hypothesize that R-421 will prevent co-stimulation and thus the downstream proliferation and activation of Th1 CD4+ cells in RA. We now propose to extend the protective effects of the R-421 technology beyond the published findings in neuroinflammation and establish its potential benefit in a clinically-relevant model of RA. Male DBA mice inoculated with collagen in CFA and rechallenged on Day 21 to induce autoimmune arthritis, will be treated with mR-421 (2, 4, 8 mg/kg), an irrelevant IgG1 control, or etanercept (6.25 mg/kg) beginning at the time of significant disease (Day 21), as characterized by an arthritic score of 2 (scale of 0-16). Additionally, we will include a sham control group not exposed to collagen/CFA or treatment. Animals will be monitored for clinical evidence of arthritis over a period of 6 weeks, a timepoint characterized in controls by erythema and edema of the entire paw including digits (score=12). Plasma m-R421 concentrations will be related to clinical outcome, so as to construct a pharmacodynamic profile that will guide future clinical dosing. We expect mR-421 to reduce joint injury, in a dose and plasma concentration dependent fashion, as defined by a reduction in the mean arthritic score that is equivalent or superior to the treatment effect elicited by the gold-standard clinically-approved agent etanercept. These findings are expected to parallel the effects of mR-421 on synovial lipid peroxidation, neutrophil infiltration, pro-inflammatory gene expression peroxynitrite production, poly(ADP-ribose)polymerase formation, and gross and histologic injury scores, and on draining lymph node populations of Th1 and Treg lymphocytes. PUBLIC HEALTH RELEVANCE: Rheumatoid arthritis is a devastating autoimmune disease characterized by lifelong disability and inexorable progression. Currently approved agents are partially effective and nearly one-third of patients do not obtain adequate relief. We are developing a novel drug that specifically blocks the specific immune disturbance that underlies this condition. We will test this agent in a clinically-relevant small animal model and determine the most effective dose, in anticipation of definitive large animal studies to confirm its efficacy and safety.