Lead Optimization of Lapatinib Analogs for Human African Trypanosomiasis

描述(由申请人提供)：需要新药来治疗人类非洲锥虫病(HAT)，这种疾病是由原始的布氏锥虫引起的。蛋白质酪氨酸(Tyr)的磷酸化在真核生物的众多细胞过程中起着重要的调节作用，而蛋白酪氨酸激酶(PTKs)抑制Tyr的磷酸化已经产生了几种耐受性良好的临床药物。在锥虫体中，Tyr的磷酸化还没有得到充分的研究，而且Tyr的磷酸化途径还没有被用来生产新的先导药物。我们的长期项目目标是(I)使用表型分析来发现抑制锥虫蛋白Tyr磷酸化的化学支架；(Ii)优化支架以用于 在保持对宿主细胞的杀锥虫活性的选择性的同时，药代动力学和物理化学性质；(Iii)确定与优化的先导结合的靶点；以及(Iv)在HAT的急性和慢性小鼠模型中评估表现最佳的优化类似物。为了实现这些目标，我们对针对人酪氨酸激酶的药物进行了重点化学筛选，并确定了7种在低微摩尔浓度下杀死无菌血流布氏锥虫的药物。随后，我们在HAT的小鼠模型中测试了其中三种药物，发现人类酪氨酸激酶抑制剂拉帕替尼(GlaxoSmithKline)可以控制锥虫感染，并治愈25%感染这种寄生虫的小鼠；因此，我们认为拉帕替尼是一种“先导”化合物。我们启动了一项先导优化计划，在针对布鲁氏毛滴虫的表型分析中，已经产生了7种具有纳摩尔活性的新化合物。我们将以我们发现的有效浓度为42纳摩尔的NEU617为重点，继续优化拉帕替尼类似物，以实现更好的药代动力学、物理化学和改善的选择性和毒性曲线。以拉帕替尼为原型，我们已经开发了多种方法来识别这些有效的新线索的靶标，我们将应用这些技术来识别我们优化的线索的靶标，并从化学和遗传学上验证潜在药物的靶标。这些优化研究中最好的化合物将在HAT小鼠模型中进行疗效评估。

DESCRIPTION (provided by applicant): New drugs are needed for treatment of the disease human African trypanosomiasis (HAT) that is caused by the protist Trypanosoma brucei. Protein tyrosine (Tyr) phosphorylation is important for regulating numerous cellular processes in eukaryotes, and inhibition of Tyr phosphorylation by protein Tyr kinases (PTKs) has yielded several well-tolerated drugs that are in clinical use. In trypanosomes, Tyr phosphorylation is understudied, and the Tyr phosphorylation pathway has not been exploited to produce new lead drugs. Our long-term project goals are to (i) employ phenotypic assays to discover chemical scaffolds that inhibit Tyr phosphorylation of trypanosome proteins; (ii) optimize the scaffolds for pharmacokinetic, and physicochemical properties while preserving selectivity in trypanocidal activity over host cells; (iii) identify targets that bind the optimized leads; and (iv) evaluate te best-performing optimized analogs in acute and chronic murine models of HAT. Towards these goals, we have performed a focused chemical screen of drugs directed against human Tyr kinases, and identified 7 hits that killed axenic bloodstream T. brucei at low micromolar concentrations. Subsequently, we tested three of the drugs in a mouse model of HAT and found that the human Tyr kinase inhibitor lapatinib (GlaxoSmithKline) controls the trypanosome infection and cures 25% of mice infected with the parasite; we therefore deemed lapatinib to be a "Lead" compound. We initiated a lead optimization program that has produced 7 novel compounds with nanomolar activity in phenotypic assays against bloodstream T. brucei. We will pivot on our discovery of NEU617 which has an effective concentration of 42 nanomolar, to continue our optimization of lapatinib analogs to achieve better pharmacokinetic, physicochemical and improved selectivity and toxicity profiles. Using lapatinib as the prototype, we have developed multiple approaches for identifying the targets of these potent novel leads, and we will apply these techniques to identify targets of our optimized leads, and to chemically and genetically validate targets of the potential drugs. The best compounds from these optimization studies will be evaluated for efficacy in murine models of HAT.