Design and Synthesis of HIV Integrase as Potential Anti-AIDS Drugs

HIV-1整合酶(IN)抑制剂是最新的抗艾滋病药物。默克的Raltegravir(Ral)(2007年10月)和Gilead的elvitegravir(EVG)(2012年8月)是FDA批准的第一批两种IN抑制剂。这些药物是一类名为“IN链转移抑制剂”(INSTI)的药物的成员，因为与酶3‘-加工(3’-P)反应相比，它们能够优先阻断酶的链转移(ST)反应。RAR和EVG治疗选择耐药类型的艾滋病毒，对这两种药物有相当大的交叉耐药性。葛兰素史克的多洛替格列韦(DTG)于2013年8月被FDA批准为第二代INSTI，它提高了对Ral和EVG耐药HIV毒株的疗效。然而，DTG也选择艾滋病毒的耐药株，强调需要继续开发能够克服IN耐药株的药物，包括新出现的DTG耐药株。利用我的实验室的设计和合成能力，我们与药理学家(NCI的伊夫·波米尔博士)、病毒学家(休斯博士，NCI)和结构生物学家(伦敦研究所的Cherepanov博士)合作开发新的IN抑制剂。这些努力导致了1-hydroxy-1，8-naphthyridin-2H-one-3-carboxamides，的发现，它在生化检测中有效地抑制了野生型(WT)IN，并在艾滋病毒1传染性的单轮感染检测中显示出良好的抗病毒效果。重要的是，这一系列的成员在后一种检测中保持了良好的抗病毒效力，以对抗耐药突变株。最近，我们发现通过对1-羟基-2-氧代-1，8-萘啶支架的6位进行修饰，我们能够获得对整个病毒具有低纳摩尔效力的INSTI，包括典型的抗INSTI的IN变体。这些化合物的特点是细胞毒性低，在某些情况下，选择性指数(CC50/EC50)大于10,000。在与Cherepanov博士的合作下，我们获得了我们的铅抑制剂与泡沫病毒(PFV)原型“整合体”(带有底物DNA的四聚体整合酶)结合的共晶结构。这些数据阐明了化合物作用的结构基础，并提供了可能有助于进一步优化生化效率的关键见解。与IN一样，HIV-1聚合酶(POL)和逆转录物(RT)的RNase H结构域也属于多核苷酸转移酶超家族，它们具有相似的催化机制，涉及两个二价金属离子。我们发现最近的INSTI成员抑制RT的POL和RNaseH活性。进一步开发针对这些靶点的抑制剂的工作正在进行中。

Inhibitors of HIV-1 integrase (IN) inhibitors represent the most recent anti-AIDS drugs. Merck's raltegravir (RAL) (October 2007) and Gilead's elvitegravir (EVG) (August 2012) were the first two IN inhibitors to be approved by the FDA. These agents are members of a class of drugs called "IN strand transfer inhibitors" (INSTIs), due to their ability to preferentially block the enzyme's strand transfer (ST) reaction as compared to the enzymes 3'-processing (3'-P) reaction. Treatment with RAL and EVG selects for resistant forms of HIV and there is considerable cross-resistance to these two drugs. GlaxoSmithKline's dolutegravir (DTG) was approved by the FDA in August of 2013 as a 2nd-generation INSTI having improved efficacies against RAL and EVG-resistant strains of HIV. However, DTG also selects for resistant strains of HIV, emphasizing the need for continued development of agents that can overcome resistant strains of IN, including the emerging DTG-resistant strains. Utilizing my laboratory's design and synthetic capabilities, we have teamed with pharmacologists (Dr. Yves Pommier, NCI), virologists (Dr. Hughes, NCI) and structural biologists (Dr. Cherepanov, London Research Institute) to develop new IN inhibitors. These efforts have resulted in the discovery of 1-hydroxy-1,8-naphthyridin-2H-one-3-carboxamides, which potently inhibit wild-type (WT) IN in biochemical assays and show good anti-viral efficacies in single-round infection assays of HIV-1 infectivity. Importantly, members of this series retain good anti-viral potency against RAL-resistant mutants in the latter assays. More recently, we have found by introducing modifications to the 6-position of the 1-hydroxy-2-oxo-1, 8-naphthyridine scaffold, that we are able to obtain INSTIs with low nanomolar potencies against an entire panel of viruses, including the canonical INSTI-resistant IN variants. The compounds are characterized by low cytotoxicities, which in several cases, results in selectivity indices (CC50/EC50) of greater than 10,000. In collaboration with Dr. Cherepanov, we have obtained co-crystal structures of our lead inhibitors bound to the prototype foamy virus (PFV) "intasome" (tetrameric integrase with substrate DNA). This data clarifies the structural basis of the compounds' actions and provides key insights that may be useful in further optimizing biochemical efficacies. Along with IN, the HIV-1 polymerase (Pol) and RNase H domains of reverse transcriptate (RT), belong to a superfamily of polynucleotidyl transferases that share a similar catalytic mechanism involving two divalent metal ions. We have found that members of our recent INSTIs inhibit both the Pol and RNase H activities of RT. Work is in progress to further develop inhibitors directed at these targets.