Optimization of Novel Small Molecules to Antagonize FGF-23

成纤维细胞生长因子-23是一种骨源性磷酸盐和维生素D调节激素，可激活FGFR/α-Klotho二元 肾脏中的复合体。循环中的成纤维细胞生长因子-23增加导致X连锁(XLH)和常染色体隐性遗传(ARH) 低磷血症，以及其他遗传性和获得性低磷血症。适应性增长 在慢性肾脏疾病(CKD)中也维持磷酸盐和维生素D的动态平衡，并与之相关。 与心血管(CV)死亡率增加有关。KRN23，一种新近批准的抗成纤维细胞生长因子-23封闭抗体 治疗XLH半衰期长，需要全身给药，剂量滴定困难，潜伏期长。 TIAL过度抑制成纤维细胞生长因子-23。由于潜在毒性，KRN23不被批准用于治疗升高的成纤维细胞生长因子-23 在CKD中。有机会开发可滴定的、口服生物利用的、短效的小分子，这些小分子可以 可明显抑制成纤维细胞生长因子-23与FGFR/α-Klotho复合体的结合。我们的中心假设是一个小分子 成纤维细胞生长因子-23拮抗剂的开发具有更灵活的剂量滴定和更短的半衰期 可有效治疗低磷血症，并可扩大预防成纤维细胞生长因子的治疗适应证。 23例慢性肾功能不全患者发生脑血管并发症。使用基于计算的、基于结构的高通量筛选，我们知道- 命名为一种治疗用的先导化合物MD-3和几个类似物。我们的目标是将原型销售线索开发成 临床前候选药物，用于治疗由成纤维细胞生长因子-23过量引起的疾病。我们的具体目标是： 1)优化新型成纤维细胞生长因子-23拮抗剂的药效。我们将阐明结构与活性的关系 (Sar)小分子成纤维细胞生长因子-23拮抗剂，以增加其效力。几种化合物的IC50&lt；500 ηM和%max Response&gt；与Aim 2中检测的可药用性检测的成纤维细胞生长因子阻断抗体相比，为75%) 进行体外吸收、分布、代谢和排泄(ADME)、药代动力学(PK)和 毒性筛选。我们将进行早期的体外ADME筛选，以确定符合最佳阈值的化合物。 ODDS(溶解度10微米，在人肝微粒体中的稳定性为tü&gt；30min，通透性1.01E-6 cm/S， 蛋白质结合(血浆，人)&lt；98%)，随后是评估CYP抑制的体外毒性/安全筛选 (5种主要同工酶的IC50和GT；10微米)，遗传毒性(Ames)，心脏毒性(HERG结合IC50和GT；10微米)，细胞- 毒性(HepG2、IC50和GT；100微米)和脱靶效应。通过体外毒性筛选的化合物将 进展到体内PK/暴露分析(tç&gt；60分钟)。3)在临床前模型中检测成纤维细胞生长因子-23拮抗剂 成纤维细胞生长因子-23过度表达。我们选择了2到3种符合最佳类药物特性的成纤维细胞生长因子-23拮抗剂，并对其进行了测试 能够治疗Hyp和Dmp1缺失的XLH和ARH临床前小鼠模型。我们还将确定成纤维细胞生长因子-23 在CKD小鼠模型中，可以通过滴定拮抗剂来预防心血管并发症，而不会导致过度兴奋。 缺铁性贫血。我们的预期结果是鉴定出具有优势的小分子成纤维细胞生长因子-23拮抗剂 过多的现有生物制品。我们的影响将是确定适合开发为新疗法的化合物 遗传性低磷血症，并可能是一种在慢性肾脏病中拮抗成纤维细胞生长因子-23的新方法。

FGF-23 is a bone-derived phosphate and vitamin D regulating hormone that activates FGFR/α-Klotho binary complexes in the kidney. Increased circulating FGF-23 causes X-linked (XLH) and autosomal recessive (ARH) hypophosphatemia, as well as other hereditary and acquired hypophosphatemic disorders. Adaptive increases in FGF-23 also maintain phosphate and vitamin D homeostasis in chronic kidney disease (CKD) and is associ- ated with increased cardiovascular (CV) mortality. KRN23, a recently approved FGF-23 blocking antibody for treating XLH, is limited by a long half-life, need for systemic administration, difficult dose titration, and the poten- tial to over-suppress FGF-23. Due to potential toxicity, KRN23 is not approved for treatment of elevated FGF-23 in CKD. There is an opportunity to develop titratable, orally bioavailable, short-acting small molecules that re- versibly inhibit FGF-23 binding to FGFR/α-Klotho complexes. Our central hypothesis is that a small molecule FGF-23 antagonist can be developed with a more flexible dose-titration and shorter half-life that will be the pre- ferred treatment of hypophosphatemic disorders, and may expand the therapeutic indication to preventing FGF- 23 mediated CV complications in CKD. Using a computational, structure-based high-throughput screen, we iden- tified a therapeutic lead compound, MD-3 and several analogs. Our goal is to develop prototypic leads into a preclinical drug candidate for the treatment of disorders caused by FGF-23 excess. Our Specific Aims are to: 1) Optimize the potency of novel FGF-23 antagonists. We will elucidate the structure-activity relationship (SAR) of small molecule FGF-23 antagonists to increase their potency. Several compounds with an IC50 < 500 ηM and % max response > 75% compared to an FGF-blocking antibody examined for druggability in Aim 2. 2) Perform in vitro absorption, distribution, metabolism and excretion (ADME), pharmacokinetic (PK) and toxicity screens. We will perform early in-vitro ADME screens to identify compounds that meet optimal thresh- olds (solubility > 10 µM, stability in human liver microsomes with a t ½ > 30 min, permeability 1.0 1E-6cm/s, protein binding (plasma, human) < 98%), followed by in-vitro toxicity/safety screens that evaluate CYP inhibition (IC50 > 10 µM for 5 major isozymes), genotoxicity (AMES), cardiac toxicity (hERG binding IC50 > 10 µM), cyto- toxicity (HepG2, IC50 > 100 µM), and off-target effects. Compounds that pass the in-vitro toxicity screen will advance to in vivo PK/exposure profiling (t ½ > 60 min). 3) Test FGF-23 antagonists in pre-clinical models of FGF-23 excess. We select 2 to 3 FGF-23 antagonists that meet the optimal drug-like properties and test their ability to treat Hyp and Dmp1 null pre-clinical mouse models of XLH and ARH. We will also determine if FGF-23 antagonists can be titrated to prevent CV complications in mouse models of CKD without inducing hyperphos- phatemia. Our expected outcomes are identification of small molecule FGF-23 antagonists with advantages over current biologicals. Our impact will be to identify compounds suitable for development into novel treatments of hereditary hypophosphatemic disorders, and possibly a new approach to antagonize FGF-23 in CKD.