The activation of benzoxaborole prodrug AN15368, a clinical candidate for Chagas disease

项目摘要 由原生动物寄生虫克氏锥虫引起的查加斯病是美洲的地方病，但也 全球化是由于人类的迁徙。尽管它是感染性心脏病的主要原因之一 在世界范围内，目前对恰加斯病的治疗具有不一致的疗效和频繁的副作用。一个主要 治疗失败的原因被认为是T细胞内短暂休眠的形式。耐药的cruzi 涉及另外高效的杀锥虫化合物。新发现的苯并氧杂硼杂环戊烯AN 15368代表了 第一个广泛验证和安全的治疗南美锥虫病的临床候选药物。随着mRNA的加工 作为表观靶点，AN 15368作为前药，需要被寄生虫丝氨酸羧肽酶裂解 （TcCBPs）以产生活性代谢物。本提案旨在进一步了解该处理步骤， AN 15368作为前药，以及评估随着该化合物向 人体临床试验 Aim 1将利用我们完善的定量质谱平台进行广泛的研究 AN 15368在T.克鲁兹一 将在本研究的基础上构建浓度梯度模型来检验只有前药，但 未处理的表单，可以输入T。Cruzi一旦被有效地处理，就在其中积累。而且这些 动力学研究将阐明外鞭毛体和无鞭毛体对AN 15368的不同敏感性， 了解前药代谢的过程。目的2将集中在药物治疗中对前药的敏感性的广度。 无鞭毛体种群将开发一种荧光底物，以允许定量前药活化， 个体无鞭毛体，包括暂时休眠的。我们将检验这样一个假设， 前药在无鞭毛体中的应用范围很广，包括休眠的无鞭毛体。最后，由于前药特性使AN 15368 通过失去加工途径获得选择性抗性的可能性，我们建议实施目标3， 当TcCBP被破坏时，在有和没有AN 15368治疗的情况下，全面监测感染的结果。 这将为这种耐药性（如果发生）的风险提供评估。 这项工作将进一步加深我们对前体药物AN 15368如何实现T. cruzi 感染，并将是第一项试图量化休眠寄生虫代谢过程的研究，以解决药物- 中介治愈这些研究的结果预计将提供对高治疗潜力的见解， 苯并氧杂硼杂环戊烯在这种和其他寄生虫感染，以及诱导耐药性的风险之一， 这类化合物，从而告知这种临床候选药物的安全性和有效性。

PROJECT SUMMARY Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, is endemic in the Americas, but has also globalized due to human migration. Despite being one of the major causes of infection-induced heart disease worldwide, current therapies for Chagas disease have inconsistent efficacy and frequent side effects. A major contributor to treatment failure is thought to be the transiently dormant intracellular forms of T. cruzi that are resistant to otherwise highly effective trypanocidal compounds. The newly discovered benzoxaborole AN15368 represents the first extensively validated and safe clinical candidate for the treatment of Chagas disease. With the mRNA processing pathway as the apparent target, AN15368 acts as a prodrug that requires cleavage by parasite serine carboxypeptidases (TcCBPs) to yield the active metabolite. This proposal aims to gain additional understanding of this processing step for AN15368 as a prodrug, as well as to assess the potential for acquired resistance as this compound proceeds toward human clinical trials. Aim 1 will take advantage of our well-established quantitative mass spectrometry platform to extensively study the kinetics of AN15368 metabolism in amastigotes and epimastigotes, the two proliferative life stages of T. cruzi. A concentration-gradient model will be constructed based on this study to test the hypothesis that only the prodrug, but not the processed form, can enter T. cruzi efficiently and once processed, accumulates therein. Furthermore, these kinetic studies will address the differential susceptibility of epimastigotes and amastigotes to AN15368 to further understand the process of prodrug metabolism. Aim 2 will focus on the breadth of susceptibility to the prodrug in the amastigote populations. A fluorogenic substrate will be developed to allow for the quantitation of prodrug activation in individual amastigotes, including the transient dormant ones. We will test the hypothesis that the susceptibility to this prodrug is broad in amastigotes, including those in dormancy. Lastly, since the prodrug feature brings AN15368 the liability of acquiring selected resistance via loss of the processing pathway, we propose to carry out Aim 3 to comprehensively monitor the outcome of infection when TcCBPs are disrupted, with and without AN15368 treatment. This will provide an assessment for the risk of this resistance if developed. The proposed work will enhance our understanding of how prodrug AN15368 achieves sterile cure of T. cruzi infection, and will be the first study attempting to quantify a metabolic process in dormant parasites to address drug- mediated cure. The results of these studies are expected to provide insights into the high therapeutic potential of benzoxaboroles in this and other parasitic infection, as well as one of the risks for induction of drug resistance to this class of compounds and thus inform on the safety and efficacy of this clinical candidate.