Development of novel small-molecule inhibitors of HIV-1 fusion as microbicides

描述(申请人提供)：CAPRISA 004替诺福韦凝胶试验的阳性数据激发了人们对开发艾滋病毒-1进入抑制剂作为局部杀微生物剂或甚至系统地提供预防艾滋病毒-1性传播的药物的极大兴趣。虽然人们在发现和开发通过靶向gp41亚单位抑制HIV-1包膜糖蛋白(Env)介导的病毒-细胞融合的小分子药物方面已经做出了相当大的努力，但这些化合物都没有成功地在局部杀菌剂的临床开发中取得进展。这项研究计划的长期目标是开发一种安全高效的低分子gp41融合抑制剂，作为抗HIV-1杀微生物剂的活性成分。在初步工作中，我们已经确定了HIV-1融合抑制物苯磺酰胺衍生物(PSD)的新靶点，该靶点首次在Env介导的细胞-细胞融合抑制物筛选中确定。该化合物与gp41亚区内保守的疏水口袋结合。我们证明了新的PSD类似物有效地抑制了具有不同地理来源和共受体要求的原代HIV-1分离株对人类T细胞的体外感染。我们定义了PSD的临时结构-活性关系(SAR)。结构数据和SAR表明，PSD的修饰可以改善效力和药理特性。我们建议利用在前期工作中开发的结构数据、SAR和合成程序来设计、合成和评估新的PSD类似物，这些类似物对广谱的性传播药物敏感和抗药性HIV-1毒株具有增强的疗效。为了实现我们的目标，我们制定了以下具体目标：1.利用gp41融合抑制剂-靶标相互作用的结构原理来优化PSD的抗病毒效力和杀菌性能。2.评价新型PSD的药效、广度和协同作用、抗病毒活性和耐药性的分子基础、理化性质以及体外和体内毒性。3.评价新型PSD在体内外对HIV-1感染的黏膜保护作用。这些目标的动机是有机会验证新的gp41疏水口袋作为抑制剂结合的目标，基于我们确定的特定抑制剂-目标位点相互作用，这些相互作用是HIV-1 gp41在细胞进入中基于结构的拮抗作用的基础，并且可以加强以提高效力和广谱活性。我们能够拼凑出这些抑制物-靶点相互作用的定量图像，为合理开发新的小分子gp41融合抑制物用于预防和/或治疗干预HIV-1感染奠定了基础。

DESCRIPTION (provided by applicant): Positive data from the CAPRISA 004 trial of tenofovir gel have stimulated tremendous interest in development of HIV-1 entry inhibitors as topical microbicides or even systematically delivered prophylactic drugs to prevent the sexual transmission of HIV-1. While considerable effort has gone into discovering and developing small-molecule agents that inhibit HIV-1 envelope glycoprotein (Env)-mediated virus-cell fusion by targeting the gp41 subunit, none of these compounds has successfully advanced in clinical development of topical microbicides. The long-term objective of this research plan is to develop a safe and highly effective low-molecular-weight gp41 fusion inhibitor for use as an active ingredient in anti-HIV-1 microbicides. In preliminary work, we have identified the novel target of the HIV-1 fusion inhibitor phenyl sulfonamide derivative (PSD) that was first identified in an Env-mediated cell-cell fusion inhibitor screen. This compound binds to a conserved hydrophobic pocket within a subdomain of gp41. We demonstrate that new PSD analogs potently inhibit in vitro infection of human T cells by primary HIV-1 isolates with different geographic origins and co-receptor requirements. We have defined a provisional structure-activity relationship (SAR) for PSDs. The structural data and SAR suggest PSD modifications that could improve potency and pharmacological properties. We propose to leverage the structural data, SAR and synthetic procedures developed in preliminary work to design, synthesize and evaluate novel PSD analogs that have enhanced efficacy against a broad-spectrum of sexually transmitted drug-sensitive and drug-resistant HIV-1 strains. To achieve our goals we have developed the following specific aims: 1. To utilize the structural principles of gp41 fusion inhibitor-target interactions to optimize the antiviral potency and microbicidal properties of PSDs. 2. To evaluate the potency, breadth and synergistic interactions, the molecular basis for antiviral activity and resistance, the physicochemical properties and the in vitro and in vivo toxicity of novel PSDs. 3. To evaluate the effectiveness of novel PSDs in mucosal protection against HIV-1 infection in vitro and in vivo. These aims are motivated by the opportunity to validate the novel gp41 hydrophobic pocket as the target of inhibitor binding, based on our identification of specific inhibitor-target site interactions that underlie structure-based antagonism of HIV-1 gp41 function in cell entry and that can be strengthened to improve potency and broad-spectrum activity. Our ability to piece together a quantitative picture of these inhibitor-target interactions sets the stge for rational development of new small-molecule gp41 fusion inhibitors for prophylactic and/or therapeutic intervention of HIV-1 infection.