PANK Activators for the treatment of pantothenate kinase-associated neurodegeneration

摘要 泛酸激酶相关神经退行性变是一种罕见的进行性神经退行性疾病。 与大脑中的铁积累有关。这种疾病会导致早期行动不便，通常会在早期死亡。 成人期。PKAN是由四个人类泛酸激酶基因之一PANK2基因突变引起的，PANK2基因 编码一种线粒体泛酸酸激酶。与人类PKAN的临床表现一致，细胞 患者来源细胞的生物学分析以及PKAN小鼠模型的表型特征 已经证明，PANK2活性的丧失会导致重大的代谢、细胞和生理缺陷。 我们最近发现，PKAN病具有大量大量线粒体疾病的特征 有丝分裂体堆积。这导致我们发现了一种新的生物标记物，可以用来 使用细胞成像技术区分PKAN和正常细胞。到目前为止，还没有特效或既定的治疗方法 存在针对PKAN的治疗，大多数治疗针对的是控制症状和减缓疾病进展。 我们假设人PANK3(HPANK3)酶的激活会导致辅酶A的刺激 在PANK2突变细胞中产生，将是治疗PKAN的理想方法。化学筛选和 确定9个人PANK3激活剂的铅化学类型的后续药物化学优化(SAR) (VTAC1-9)，强烈激活AC50值在NM范围内的hPANK3。这些化合物不会影响 人PANK1或PANK2的活性，对四个人类细胞系和一个原代人类细胞没有毒性， 并具有理想的官能度和溶解性。早期铅在小鼠体内的药代动力学研究 VTAC1和VTAC2显示出血浆和脑暴露，良好的时间，没有明显的毒性。 总而言之，这些数据表明，这些化合物是开发有效和 安全的PKAN疗法。拟议研究的目标是对Active进行详细的表征 VTAC及其类似物库，以识别可用于未来临床的晚期导联 发展。为此，我们将追求以下三个具体目标。在目标1中，我们将完成 通过对该家族化合物的生化活性、选择性和物理性质的表征，对该家族化合物进行了研究。 已合成的29个类似物和另外200个待评价的化合物的化学性质 以迭代为基础。在目标2中，我们将进行基于细胞的分析，以确定在体外具有优良性能的化合物。 治疗指标，并能恢复Pank2缺陷细胞的生物活性。在目标3中，我们将进行ADME 和PK分析和评估VTAC1和VTAC2的体内疗效以及来自Pank2-/-的Aim 1的新导联 通过监测重要的PKAN生物学指标，包括CoA代谢途径铁的激活 动态平衡、线粒体代谢和PKAN样表型的挽救。这些研究的成功将 为hPANK3先导激活剂作为一种可能有效和安全的治疗方法的未来临床评估奠定基础 对于PKAN来说。

SUMMARY Pantothenate kinase-associated neurodegeneration, PKAN, is a rare progressive neurodegenerative disorder associated with iron accumulation in the brain. The disease causes early immobility and often death by early adulthood. PKAN is caused by mutations in one of four human pantothenate kinase genes, PANK2 gene, which encodes a mitochondrial pantothenate kinase. Consistent with the clinical presentation of PKAN in humans, cell biological analyses from patient-derived cells as well as phenotypic characterization of mouse models of PKAN have demonstrated that the loss of PANK2 activity results in major metabolic, cellular and physiological defects. We have recently discovered that PKAN disease has the hallmarks of a mitochondrial disorder with large accumulation of mitophagosomes. This has led us to discover a novel biomarker that could be used to differentiate between PKAN and normal cells using cell imaging. To date, no specific or established therapy exists for PKAN with most treatments directed towards managing symptoms and to slow disease progression. We hypothesize that activation of the human PANK3 (hPANK3) enzyme would result in stimulation of CoA production in PANK2 mutated cells and would represent an ideal treatment of PKAN. Chemical screening and subsequent medicinal chemistry optimization (SAR) of the lead chemotype identified 9 human PANK3 activators (VTAC1-9) that strongly activate hPANK3 with AC50 values in the nM range. These compounds do not affect the activity of human PANK1 or PANK2, show no toxicity against four human cell lines and one primary human cell, and have desirable functionality and solubility properties. Pharmacokinetics studies in mice with the early leads VTAC1 and VTAC2 demonstrated both plasma and brain exposure, excellent t½, and no apparent toxicity. Together these data indicate that these compounds are ideal candidates for the development of an effective and safe PKAN therapy. The goal of the proposed research is to conduct detailed characterization of active VTACs and a library of their analogs to identify late leads that could be advanced towards future clinical development. Towards this end, we will pursue the following three specific aims. In Aim 1, we will complete current SAR on this family compounds by characterizing the biochemical activity, selectivity and physico- chemical properties of an already synthesized 29 analogs and an additional 200 compounds to be evaluated on an iterative basis. In Aim 2, we will conduct cell-based assays to identify compounds with excellent in vitro therapeutic index and can restore biological activity in pank2-deficient cells. In Aim 3, we will conduct ADME and PK analyses and evaluate the in vivo efficacy of VTAC1 and VTAC2 and new leads from Aim 1 in pank2-/- mice by monitoring important PKAN biological metrics including activation of the CoA metabolic pathway, iron homeostasis, mitochondrial metabolism, and rescue of PKAN-like phenotypes. The success of these studies will set the stage for future clinical evaluation of a lead activator of hPANK3 as a possible effective and safe treatment for PKAN.