Tropism, Susceptibility and Resistance Deteminants

迫切需要针对病毒复制周期不同阶段的新的HIV-1疗法，以对抗日益流行的多药耐药病毒并减少治疗毒性。趋化因子受体CCR 5通过与HIV-1的主要受体CD 4结合作为融合辅助受体而充当HIV-1进入的关键门户。CCR 5在病毒传播和发病机制中起着核心作用，因此代表了新的HIV-1疗法的有吸引力的靶点。PRO 140是一种独特的人源化CCR 5单克隆抗体（mAb），提供了一种新的治疗特征。与正在开发的小分子CCR 5拮抗剂不同，PRO 140广泛有效地抑制CCR 5介导的HIV-1进入，而不会阻断或以其他方式失调CCR 5的天然活性。此外，PRO 140在健康志愿者中正在进行的Ia期临床试验中显示出良好的耐受性和药代动力学特征。PRO 140在缺乏CCR 5拮抗作用、病毒耐药性的非重叠模式、抗病毒协同作用、优异的耐受性特征和罕见（例如，每月）给药。因此，PRO 140可能定义了一个独特的CCR 5抑制剂亚类，我们将在项目1中探讨这个问题。这种治疗方法的高度创新性进一步强调了没有CCR 5抑制剂和针对任何靶点的mAb被批准用于HIV-1治疗的事实。在项目3中，我们将利用新的表型和基因型技术来检测病毒对PRO 140的嗜性、易感性和耐药性。初步研究将使用从6000个成员的ViroLogic文库中选择的广泛病毒组探索PRO 140敏感性的自然变异，重点是潜在的关键控制参数。本项目的主要重点是监测在项目2的临床试验中接受PRO 140治疗的患者的辅助受体使用和PRO 140敏感性。在这种情况下，我们将确定符合条件的纯R5病毒研究患者，我们将监测研究参与者的辅助受体使用或PRO 140敏感性的任何变化。我们将检查是否有任何耐药变异代表了先前存在的次要种属的产物， 是对治疗反应的序列进化的结果。将在体外分析变异体，以确定其分子机制和耐药的遗传决定因素、对HIV-1进入和酶抑制剂的交叉耐药模式以及内在融合性。我们的实验室研究将与摩尔博士（项目1）合作进行，我们将使用不同的研究方法来解决一系列互补的问题。项目3对于开展项目2的首次HIV临床研究以及通过一系列临床前和临床概念验证研究将PRO 140从创新治疗概念最佳转化为有前途的新研究药物的总体IPCP目标至关重要。

There is an urgent need for new HIV-1 therapies targeting different steps of the viral replicative cycle to combat the growing prevalence of multidrug-resistant viruses and to reduce treatment toxicities. The chemokine receptor CCR5 serves as a critical portal of HIV-1 entry by acting as a fusion coreceptor in conjunction with CD4, the primary receptor for HIV-1. CCR5 plays a central role in virus transmission and pathogenesis, and therefore represents an attractive target for new HIV-1 therapies. PRO 140 is a unique humanized CCR5 monoclonal antibody (mAb) that offers a novel therapeutic profile. Unlike small-molecule CCR5 antagonists under development, PRO 140 broadly and potently inhibits CCR5-mediated HIV-1 entry without blocking or otherwise dysregulating the natural activities of CCR5. In addition, PRO 140 has demonstrated favorable tolerability and pharmacokinetic profiles in an ongoing Phase la clinical trial in healthy volunteers. PRO 140 is clearly differentiated from small molecules in terms of its lack of CCR5 antagonism, nonoverlapping patterns of viral resistance, antiviral synergy, excellent tolerability profile, and potential for infrequent (e.g., monthly) dosing. PRO 140 may therefore define a unique CCR5 inhibitor subclass, an issue that we will explore in Project 1. The highly innovative nature of this therapeutic approach is further underscored by the fact that no CCR5 inhibitor and no mAb to any target have been approved for HIV-1 therapy. In Project 3, we will utilize novel phenotypic and genotypic technologies to examine viral tropism, susceptibility and resistance to PRO 140. Initial studies will explore the natural variation in PRO 140 susceptibility using a broad panel of viruses selected from the 6000-member ViroLogic library with an emphasis on potential key controlling parameters. A primary focus of this Project is to monitor coreceptor usage and PRO 140 susceptibility in patients treated with PRO 140 in the clinical trials of Project 2. In this capacity, we will identify eligible study patients who present with pure R5 viruses, and we will monitor study participants for any change in coreceptor usage or PRO 140 susceptibility. We will examine whether any resistant variants represent outgrowth of pre-existing minor species or are the result of sequence evolution in response to therapy. The variants will be analyzed in vitro to determine their molecular mechanisms and genetic determinants of resistance, patterns of cross-resistance to HIV-1 entry and enzyme inhibitors, and intrinsic fusogenicity. Our laboratory research will be carried out in collaboration with Dr. Moore (Project 1), and we will address a complementary set of issues using distinct research methodologies. Project 3 is essential to the conduct of the first-in-HIV clinical studies of Project 2 and to the overall IPCP goal of optimally translating PRO 140 from an innovative treatment concept into a promising new investigational agent via an integrated series of preclinical and clinical proof-of-concept studies.