Development of small molecule TLR5 inhibitors for rheumatoid arthritis therapy

抽象的。 大约250万美国人患有类风湿性关节炎(RA)，这是最常见的慢性疾病之一 老年人群中的自身免疫性疾病。类风湿性关节炎无法治愈，高达40%的患者无法治愈 对目前的治疗方法有反应。因此，疾病的发展会导致关节破坏和严重残疾 老年人。因此，确定一种新的治疗策略单独使用或联合使用 现有的治疗方法将解决RA治疗中的一个关键障碍。该项目的总体目标是解决 通过开发用于RA治疗的新型小分子药物来满足这一未得到满足的医疗需求。我们的战略是建立 基于两个新的发现：(A)Toll样受体5(TLR5)在类风湿关节炎中的重要作用，以及(B)一个新的 化学系列小分子TLR5抑制剂。初步研究表明，TLR5高度升高 RA髓系细胞与正常髓系细胞相比，其表达与RA疾病密切相关 活动评分(DAS28)。此外，TLR5与其在关节中表达的天然配体的连接使RA 外周血(PB)髓系细胞转化为促炎M1巨噬细胞和成熟破骨细胞。在老鼠身上， 全身和局部注射TLR5激动剂会加剧关节肿胀和骨质侵蚀。反之，反- TLR5抗体治疗减轻胶原性关节炎(CIA)关节炎症和骨骼 毁灭。与这些研究一致的是，合作者发现了小分子TLR5抑制剂 拮抗TLR5与其激动剂鞭毛蛋白之间的相互作用 假单胞菌和伯克霍尔德氏菌。来自筛查的几个有效命中在RA PB髓系细胞中有效。 具体地说，2-亚氨基苯并咪唑烯(IBZ)系列化合物可消除RA M1巨噬细胞 比抗肿瘤坏死因子抗体、抗IL-6R抗体或TLR4更有效地分化和破骨细胞成熟 拮抗剂和几个类似物可使鞭毛蛋白诱导的RA产生的肿瘤坏死因子、白介素6和CCL2减少高达70% 具有低细胞毒性的PB髓系细胞，产生~gt；10的选择性指数和响应性结构-活性 将指导进一步的化学优化的关系(SAR)。所有三个激活的模拟都显示良好 在小鼠肝微粒体+NADPH和水溶液中的稳定性(90%，84%和74%) 在这一转化药物开发项目的第一阶段，所有3个类似物的溶解度都超过400微米， IBZ系列将经过化学优化，以最大限度地提高效力和选择性以及类药物吸收， 分布、代谢和排泄(ADME)特性及其作用机制 将确定IBZ系列的靶标特异性。来自TLR5抑制筛选的其他化合物 MBX将作为这个项目的后备脚手架。在第二阶段，体内验证的导联和临床前 候选者将从IBZ系列中通过在小鼠中制定和评估优先类似物来确定 胶原性关节炎小鼠最大耐受量、药代动力学和疗效的测定 模特。在第三阶段，临床前候选方案的有效性将与其他方案进行比较 使用急慢性类风湿性关节炎临床前模型和研究新药的现有治疗方法 (IND)将开展启用毒理学和安全药理学研究。

Abstract. Approximately 2.5 million Americans have rheumatoid arthritis (RA), which is one of the most common chronic autoimmune disorders in the older population. There is no cure for RA, and up to 40% of patients do not respond to current therapies. As a result, disease progression leads to joint destruction and severe disability in the elderly. Therefore, the identification of a novel therapeutic strategy used alone or in combination with existing therapies would resolve a critical barrier in RA treatment. The overall goal of this project is to address this unmet medical need by developing novel small molecule drugs for RA therapy. Our strategy is to build upon two new discoveries: (a) the important role of the toll-like receptor 5 (TLR5) in RA, and (b) a novel chemical series of small molecule TLR5 inhibitors. Preliminary studies revealed that TLR5 is highly elevated in RA myeloid cells as compared to normal myeloid cells, and its expression closely correlates with RA disease activity score (DAS28). Furthermore, ligation of TLR5 to its natural ligand expressed in the joints transforms RA peripheral blood (PB) myeloid cells into proinflammatory M1 macrophages and mature osteoclasts. In mice, systemic and local injection of a TLR5 agonist exacerbates joint swelling and bone erosion. Conversely, anti- TLR5 antibody (Ab) therapy attenuates collagen induced arthritis (CIA) joint inflammation and bone destruction. Coincident with these studies, collaborators discovered small molecule TLR5 inhibitors that antagonize the interaction between TLR5 and its agonist, flagellin, from bacterial infectious agents including Pseudomonas and Burkholderia. Several validated hits from the screen are effective in RA PB myeloid cells. In particular, a 2-iminobenzimidazolene (IBZ) series of compounds abrogates RA M1 macrophage differentiation and osteoclast maturation more effectively than does anti-TNF Ab, anti-IL-6R Ab or a TLR4 antagonist, and several analogs reduced flagellin induced TNF, IL-6 and CCL2 production by up to 70% in RA PB myeloid cells with low cytotoxicity, yielding a selectivity index of >10 and responsive structure–activity relationships (SAR) that will guide further chemical optimization. All three active analogs displayed good stability (90%, 84%, and 74%) in the presence of mouse liver microsomes + NADPH, and the aqueous solubility of all 3 analogs was in excess of 400 µM. In Phase I of this translational drug development project, the IBZ series will be chemically optimized to maximize potency and selectivity as well as drug-like absorption, distribution, metabolism and excretion (ADME) properties, and the mechanism of action together with the target specificity will be determined for the IBZ series. Other compounds from the TLR5 inhibition screen at MBX will serve as backup scaffolds for this project. In Phase II, in vivo-validated leads and a preclinical candidate will be identified from the IBZ series by formulating and evaluating prioritized analogs in mice to determine the maximum tolerated dose, pharmacokinetics and efficacy in a murine collagen-induced arthritis model. In Phase III, the effectiveness of the preclinical candidate will be evaluated in comparison with other currently available therapies using acute and chronic RA preclinical models, and Investigational New Drug (IND) enabling toxicology and safety pharmacology studies will be carried out.