MDR-TB Drugs: Targeting Cell Wall Synthetic Enzymes

描述（由申请人提供）：NIH通知NOT-AI-02-023的目的之一是加快导致治疗耐多药结核病（一种潜在的生物恐怖主义制剂）的研究。需要基于与现有结核病药物不同的靶点的新化疗，但缺乏可用于临床试验的所需先导药物。针对这种缺乏所需先导物的情况，建议通过开发当前药物不靶向的几种必需细胞壁合成酶的抑制剂来开发具有抗MDR-TB活性且在小鼠中有效的新先导物。 抑制三种不同细胞壁合成酶（其中一些还抑制TB的生长）的化合物已经通过用基于微量滴定板的酶测定筛选化学文库来鉴定。这些和类似鉴定的命中物将使用“化合物精制”循环精制成对耐多药结核病也有活性的高效酶抑制剂。该周期开始于“化合物开发组”对目标酶（特别是具有键抑制剂的酶）进行X射线晶体学研究，进行分子建模以设计新的抑制剂，最后基于该建模合成一组化合物，并结合化学多样性。然后，“化合物分析组”确定酶抑制的功效、对一组MDR-TB分离株的MIC值、体外细胞毒性，以及必要时确定小鼠中的毒性、干扰素γ敲除小鼠中的功效、基本药代动力学和标准小鼠模型中的功效。来自化合物分析组的数据被传递到化合物开发组，以便可以制备新一轮的进一步精制的化合物。对于每一类抑制剂，该循环持续进行，直到具有所需性质的化合物出现，或者确定特定类别的化合物不太可能产生新药。该周期目前准备好开始与三种必需酶的抑制剂;此外，我们将开发微量滴定板测定和筛选化学文库中的命中四个额外的必需细胞壁生物合成酶，然后将进入细化周期。

DESCRIPTION (provided by applicant): A purpose of NIH Notice NOT-AI-02-023 is to expedite research leading to the treatment of MDR-TB, a potential bioterrorism agent. New chemotherapies based on different targets than the present TB drugs are needed, but there is a paucity of the required leads ready for clinical trials. In response to this lack of required leads, it is proposed to develop new leads active against MDR-TB and effective in mice by developing inhibitors of several essential cell wall synthetic enzymes not targeted by current drugs. Compounds that inhibit three different cell wall synthetic enzymes (some of which also inhibit the growth of TB) have been identified by screening a chemical library with microtiter plate based enzyme assays. These and similarly identified hits will be refined into highly effective enzyme inhibitors also active against MDR-TB using a "compound refinement" cycle. The cycle begins with the "compound development group" doing X-ray crystallography studies of the targeted enzymes (especially enzymes with bond inhibitors), proceeding to molecular modeling to design new inhibitors and finally synthesizing a group of compounds based on this modeling and also incorporating chemical diversity. Then the "compound analysis group" determines efficacy of enzyme inhibition, MIC values on a panel of MDR-TB isolates, in vitro cell toxicity, and as warranted, toxicity in mice, efficacy in an interferon gamma knock out mouse, basic pharmacokinetics, and efficacy in a standard mouse model. The data from the compound analysis group is relayed to the compound development group so that a new round of further refined compounds can be prepared. The cycle is continued for each class of inhibitors until compounds with the desired properties emerge or it is determined that a particular class of compounds is unlikely to be yield new drugs. The cycle is presently ready to begin with inhibitors of three essential enzymes; in addition we will develop microtiter plate assays and screen chemical libraries for hits for four additional essential cell wall biosynthetic enzymes which will then enter the refinement cycle.