Repolarization of Activated Th1 Cells: a Novel Means to Treat IBD

描述（由申请人提供）：目前克罗恩病（CD）的治疗方案并不令人满意，该疾病并发症的高比例证明了这一点，经常需要衰弱的肠道切除术。CD被认为是由于致病性Th1/Th17细胞过量和耐受诱导抗原（Ag）特异性T调节性CD4+细胞缺乏，特别是Tr1细胞（FOXp3-CD25-IL-10high, FOXp3-CD25-IL-4high）。在缺乏适当水平的调节性t细胞的情况下，致病性Th1/Th17细胞的影响是不对抗的，导致粘膜炎症和损伤。超过粘膜完整性的阈值损失，肠道内的细菌易位发生，然后引发粘膜下感染、炎症、组织损伤和更大屏障功能障碍的正反馈循环。为了满足这一需求，Radikal Therapeutics正在开发一种新的融合蛋白（hR-411），可在抗原（Ag）特异性活化的t细胞中诱导靶向免疫耐受。hR-411是由Ig-Fc和CXCL11构建的，CXCL11是一种cxcr3结合配体，最近被鉴定为一种反调节趋化因子。用hR-411的小鼠同源物mR-411治疗，即使在疾病发作后开始治疗，也能深刻抑制实验性过敏性脑脊髓炎（EAE），这是啮齿动物的一种经典自身免疫模型系统。此外，在过继性转移实验中，从EAE供体中分离出的ag特异性效应Th1细胞在体内经mR-411处理后，可将其定向极化为Tr1细胞，抑制EAE。与泛抑制性免疫调节剂不同，mR-411诱导对活动性疾病具有ag特异性的耐受性，同时保留对先前遇到的抗原的全身免疫。我们将在重组酶激活基因-1缺陷（RAG-/-）小鼠中通过CD4+CD45RBhigh t细胞过继转移导致结肠炎，进行剂量增加的安慰剂对照研究。在过继性t细胞移植后4周开始mR-411或地塞米松治疗。mR-411有望剂量依赖性地改善肠道组织学评分并防止中性粒细胞浸润。2期具体目标：通过大鼠和灵长类动物的GLP毒理学和安全药理学研究，建立hR-411的临床前安全性。我们将开发：1)用于在无血清培养基中生产hR-411的高产CHO细胞系；2)验证分析方法，以支持生产过程和释放测试；3)gmp级hR-411原料药和产品批次，以支持GLP毒理学和安全药理学研究以及GCP临床试验。然后，我们将在狨猴非人类灵长类动物中进行急性安全药理学和亚急性和慢性毒理学研究。

DESCRIPTION (provided by applicant): Current treatment regimens for Crohn's Disease (CD) are unsatisfactory, as evidenced by the high percentage of complications in the disease, frequently necessitating debilitating intestinal resection. CD is thought to result from both an excess of pathogenic Th1/Th17 cells and a deficiency of tolerance-inducing antigen (Ag) specific T regulatory CD4+ cells, in particular Tr1 cells (FOXp3-CD25-IL-10high, FOXp3-CD25-IL-4high). In the absence of suitable levels of regulatory T-cells, the impact of pathogenic Th1/Th17 cells is unopposed, resulting in mucosal inflammation and injury. Beyond a threshold loss of mucosal integrity, bacterial translocation from the gut lumen takes place, which then elicits a positive feedback loop of submucosal infection, inflammation, tissue injury, and greater barrier dysfunction. To meet this need, Radikal Therapeutics is developing a novel fusion protein (hR-411) that induces targeted immune tolerance in antigen (Ag)-specific activated T-cells. hR-411 is constructed from Ig-Fc and CXCL11, a CXCR3-binding ligand that has been recently identified as a counter- regulatory chemokine. Therapy with mR-411, the murine homologue of hR-411, profoundly suppresses experimental allergic encephalomyelitis (EAE), a classic autoimmune model system in rodents, even when treatment is initiated after disease onset. Moreover, Ag-specific effector Th1 cells isolated from EAE donors treated in vivo with mR-411 redirect their polarization into Tr1 cells and suppress EAE in adoptive transfer experiments. In contrast to pan-suppressive immunomodulators, mR-411 induces tolerance that is Ag-specific for the active disease yet preserves generalized immunity to previously encountered antigens. Phase 1 Specific Aim: Establish that mR-411 dose-dependently attenuates established colitis in an adoptive T-cell transfer model of intestinal inflammation We will carry out a dose-escalation placebo-controlled investigation of mR-411 in recombinase-activating gene-1 deficient (RAG-/-) mice rendered colitic via the adoptive transfer of CD4+CD45RBhigh T-cells. Treatment with mR-411 or dexamethasone will begin 4 weeks after adoptive T-cell transfer. mR-411 is expected to dose-dependently improve gut histology score and prevent neutrophil infiltration. Phase 2 Specific Aim: Establish the pre-clinical safety of hR-411, as demonstrated by GLP studies of toxicology and safety pharmacology in rats and primates. We will develop: 1) a high-producing CHO cell line for production of hR-411 in serum-free media, 2) validated analytical methods to support manufacturing in- process and release testing, and 3) GMP-grade batches of hR-411 drug substance and product to support GLP toxicology and safety pharmacology studies and GCP clinical trials. We will then undertake acute safety pharmacology and subacute and chronic toxicology investigations in Marmoset non-human primates. PUBLIC HEALTH RELEVANCE: Crohn's Disease remains recalcitrant to existing therapies, with a high percentage of patients enduring recurrent bouts of inflammation and intestinal damage. We are developing a novel drug that specifically blocks the inflammatory process in this condition yet does not interfere with general immunity. We will test this agent in a clinically-relevant animal model of autoimmune colitis.