Antifungals targeting pantothenate phosphorylation

总结 侵袭性真菌感染（IFIs）造成了重大的医疗保健和经济负担，因为它们负责 全世界每年有超过10亿例感染，导致150多万人死亡。医院的病人 获得院内IFIs的患者经历更长的住院时间、更高的发病率和更高的死亡率。 只有少数几类抗真菌药物是可用的，并且所有类别内的耐药性的出现是一个挑战。 对全球公共卫生的严重威胁。特别值得关注的是由念珠菌，曲霉菌， 隐球菌属和肺孢子虫属，由于这些病原体的耐药性水平， 相关死亡率。迫切需要新的抗真菌药物，特别是随着 多药耐药菌株为了满足这一需求，Curatix正在开发一类新的抗真菌药物， 破坏必需的代谢途径和辅酶A（CoA）生物合成的第一步- 维生素B5被泛酸激酶（PanK）磷酸化。遗传学和药理学研究 证明了在真菌中，这一步骤对细胞活力至关重要，从而验证了真菌PanKs作为优良靶点 用于开发新的抗真菌药物。为了实现这一目标，我们进行了高通量 筛选~ 156，593个化合物以寻找A. Fumigatus AfPanK，并鉴定了三个第1代 单个化学型内的化合物，Ki值范围在190和360 nM之间。筛选和 对86种类似物进行初步药物化学优化，鉴定出4种第二代化合物， 提高了对AfPanK以及S.酿酒酵母PanK（Cab 1），Ki值范围为12 - 15， Cab 1为170 nM，AfPanK为50和217 nM。化合物对5种人血淋巴细胞均无细胞毒性 细胞系，对真菌PanK的选择性高于人PanK（EC 50>10 µM）， 体外抗C. albicans、假丝酵母C. parapsilosis和C.光滑的我们进一步解出了 Cab 1作为脱辅基酶并与这些抑制剂复合。第一阶段计划将建立在这些 目的是评价这些先导化合物在体内的生物活性的重要数据， 启动SAR以提高其抗真菌效力（>10倍）。在目标1中，我们将表征体内 这些化合物在念珠菌病和曲霉病的动物模型中的功效。在目标2中，我们将在 生物学、生物化学和结构数据，以生成类似物库，从而鉴定具有以下特征的化合物： 对多种真菌病原体更有效的活性。第一阶段计划的成功完成将提供 支持第二阶段计划所需的关键数据，重点是先导化合物在各种疾病中的疗效， 单独或与其它已知抗真菌药组合的真菌感染模型。PanK抑制剂的临床应用 有可能为治疗IFIs提供更有效的治疗选择，无论是作为单药治疗还是 与现有药物组合，从而大大降低与药物治疗相关的经济和医疗负担。 这些感染和改善病人的结果。

SUMMARY Invasive fungal infections (IFIs) create significant healthcare and economic burdens as they are responsible for more than one billion infections worldwide each year resulting in more than 1.5 million deaths. Hospital patients who acquire nosocomial IFIs experience longer hospital stays, increased morbidity, and higher mortality rates. Only a few classes of antifungal drugs are available, and the emergence of resistance within all classes is an alarming threat to global public health. Of particular concern are infections caused by Candida, Aspergillus, Cryptococcus, and Pneumocystis species due the level of resistance seen with these pathogens and the associated mortality rates. New classes of anti-fungals are desperately needed, particularly with the emergence of multidrug resistant strains. To address this need, Curatix is developing a new class of anti-fungals that disrupt an essential metabolic pathway and first step in coenzyme A (CoA) biosynthesis - the phosphorylation of vitamin B5 by pantothenate kinase (PanK). Genetic and pharmacological studies demonstrated that in fungi, this step is essential for cell viability, thus validating fungal PanKs as excellent targets for the development of new classes of antifungal drugs. To achieve this goal, we conducted high-throughput screen of ~156,593 compounds to search for inhibitors of A. fumigatus AfPanK and identified three 1st generation compounds within a single chemotype with Ki values ranging between 190 and 360 nM. Screening and preliminary medicinal chemistry optimization of 86 analogs identified four 2nd generation compounds with improved activity against AfPanK as well as S. cerevisiae PanK (Cab1) with Ki values ranging between 12 and 170 nM for Cab1 and 50 and 217 nM for AfPanK. The compounds showed no cytotoxicity against five human cell lines, very high selectivity for fungal PanKs over human PanKs (EC50 >10 µM), and significant biological activity in vitro against C. albicans, C. parapsilosis and C. glabrata. We further solved the crystal structure of Cab1 as an apo-enzyme and in complex with these inhibitors. This Phase I program will build upon these significant data with the goal to evaluate the biological activity of these lead compounds in vivo and initiate an SAR to improve their antifungal potency (>10 fold). In Aim 1 we will characterize the in vivo efficacy of these compounds in animal models of candidiasis and aspergillosis. In Aim 2, we will build upon the biological, biochemical and structural data to generate a library of analogs in order to identify compounds with more potent activity against multiple fungal pathogens. Successful completion of the Phase I program will provide the critical data needed to support a Phase II program focused on the efficacy of the lead compounds in various models of fungal infections alone or in combination with other known antifungals. Clinical use of a PanK inhibitor has the potential to provide a more effective therapeutic option for treating IFIs, both as monotherapy and in combination with existing drugs, thus greatly decreasing the economic and healthcare burdens associated with these infections and improving patient outcomes.