Structure Determination of the Chemokine Receptor CCR2 with Novel Inhibitors

 描述（由申请人提供）：广泛的临床前研究表明趋化因子受体CCR 2与多种炎症性疾病有关，包括多发性硬化症和其他神经退行性疾病、神经性疼痛、类风湿性关节炎和骨关节炎以及纤维化。然而，目前还没有靶向CCR2的药物通过临床试验，主要是由于疗效问题。已经提出了缺乏功效的几个原因，包括趋化因子系统的冗余，使得对于复杂的疾病适应症可能需要同时靶向另外的受体，以及由于快速的化合物解离速率而导致体内靶受体的非最佳占据。为了处理冗余问题，正在寻求同时针对CCR 2和CCR 5。为了改善潜在先导化合物的受体占有率，长停留时间（LRT，例如低解离速率）化合物也在开发中，因为预测它们的功效超过对CCR2具有等同亲和力的短停留时间化合物。此类LRT化合物还可导致改善的药物安全性，因为实现功效所需的剂量较低或频率较低。最后，CCR2的变构拮抗剂也吸引了越来越多的兴趣，因为它们以可滴定的方式调节正构调节剂的作用的潜力。尽管在开发这些新的长驻留、双靶向和变构的CCR2调节剂方面取得了很大进展，但其作用的结构基础仍然未知。这是因为作为来自GPCR家族的膜蛋白，CCR2是高度挑战性的结晶靶标。因此，本发明的目的是确定与（i）长停留时间正构拮抗剂、（ii）变构调节剂和（iii）双重CCR 2/CCR 5正构拮抗剂复合的CCR 2的晶体结构。这项工作建立在我们最近成功确定CXCR4与趋化因子复合物的结构，这是任何GPCR与蛋白质配体的第一个结构，以及CCR2与所有三种类型调节剂的稳定均匀复合物形式的强有力的初步数据的基础上。我们的中心假设是，化合物的动力学，选择性和变构起源于专门的原子水平与受体的相互作用，结构测定将揭示这些相互作用，从而使合理的设计具有优化性能的化合物。我们的长期目标是帮助开发针对CCR2和其他有治疗价值的受体的药物。这一提议的重要性是由于化合物优化工作的转化性质，这可能影响许多与CCR 2相关的疾病。该项目是创新的，因为这是第一次的结构， CCR2将被确定，并且因为关注于可能导致更好的体内功效的该受体的新型和机制多样的抑制剂。

 DESCRIPTION (provided by applicant): Extensive preclinical studies have implicated the chemokine receptor, CCR2, in numerous inflammatory diseases including multiple sclerosis and other neurodegenerative diseases, neuropathic pain, rheumatoid and osteoarthritis and fibrosis. However, at this time, no drugs targeting CCR2 have made it through clinical trials largely due to efficacy issues. Several reasons for lack of efficacy have been suggested including redundancy of the chemokine system such that additional receptors may need to be targeted simultaneously for complex disease indications, and non-optimal occupancy of the target receptor in vivo because of fast compound off- rates. To deal with redundancy, dual targeting of both CCR2 and CCR5 is being pursued. To improve receptor occupancy of potential lead compounds, long residence time (LRT, e.g. low off-rate) compounds are also under development as their efficacy is predicted to exceed short residence time compounds with equivalent affinities for CCR2. Such LRT compounds may also lead to improved drug safety because of lower or less frequent dosing required to achieve efficacy. Finally, allosteric antagonists of CCR2 are also attracting increasing interest because of their potential to regulate effects of orthosteric modulators in a titratable way. Despite the great progress towards the development of these novel long-residence, dual-targeting, and allosteric modulators of CCR2, the structural basis of their action remains unknown. This is because as a membrane protein from the GPCR family, CCR2 is a highly challenging crystallization target. The objective of the present proposal is therefore to determine crystal structures of CCR2 in complex with (i) long residence time orthosteric antagonists, (ii) allosteric modulator(s) and (iii) dual CCR2/CCR5 orthosteric antagonists. This work builds on our recent success in determining the structure of CXCR4 in complex with a chemokine, which is the first structure of any GPCR with a protein ligand, and on strong preliminary data in the form of stable homogenous complexes of CCR2 with all three types of modulators. Our central hypothesis is that compound kinetics, selectivity, and allostery originate from specialized atomic level interactions with the receptor, and that structure determination will reveal these interactions and thus enable rational design of compounds with optimized properties. Our long term goal is to aid in the development of drugs that target CCR2 and other therapeutically valuable receptors. The significance of this proposal is due to the translational nature of the work on compound optimization that may impact many diseases related to CCR2. The project is innovative because this is the first time the structure of CCR2 will be determined, and because of the focus on novel and mechanistically diverse inhibitors of this receptor that may lead to better in vivo efficacy.