Ex Vivo Model for Assessing the Vaginal Disposition of PrEP Antiretrovirals

描述(申请人提供)：全球艾滋病毒/艾滋病大流行已进入第30个年头，但感染率仍居高不下，2009年全球有260万人感染。这些令人不安的统计数字突显了有效的抗逆转录病毒化学预防作为高危人群预防措施的必要性。最近的两项大规模临床试验表明，暴露前预防(PrEP)可以预防相当大比例的个人感染。CAPRISA 004试验表明，感染艾滋病毒的妇女在性交前坚持使用1%替诺福韦阴道凝胶的方案，艾滋病毒传播率降低了54%。在Iprex试验中，与男性发生性关系的男性和变性女性每天接受一次恩曲他滨(FTC)和富马酸替诺福韦异丙酯(TDF)治疗，艾滋病毒感染减少了44%。这些非常令人鼓舞的结果为未来基于全身和局部PrEP的临床研究提供了明确的理由，可能会联合使用TDF和FTC等抗逆转录病毒药物。在为这些试验做准备时，NIAID已将开发用于评估抗逆转录病毒药物的新型体外系统确定为关键优先领域。抗逆转录病毒药物具有不可预测的药代动力学(PK)特性，涉及广泛的药物代谢和膜相关载体蛋白的转运。联合用药治疗通常会引入复杂的药物-药物相互作用，这可能导致中毒或亚治疗药物浓度，并影响治疗。本应用的目的是建立细胞培养模型，真实地重建阴道上皮细胞的膜药物转运过程，并利用这些系统研究TDF-FTC药物组合的体外跨细胞转运。生物膜的通透性是药物PK谱最重要的决定因素之一。药物通过被动的跨细胞和载体介导的过程相结合的方式通过细胞。鉴于分子转运蛋白在人类生殖道和动物模型中表达的知识匮乏，目前还不可能进行具有代表性的体外研究来预测体内PK。我们建议通过以下三个研究阶段来解决这一迫切需求：(1)测量用于评价局部杀微生物剂配方的人和动物模型中阴道组织中分子转运蛋白(膜蛋白)的基线基因表达；(2)开发体外模型并将其应用于TDF-FTC组合，通过创建新的，并利用现有的， 阴道细胞培养系统；以及(3)通过将TDF和FTC局部输送到生殖道的阴道内环进行体内PK研究，评估体外模型预测。

DESCRIPTION (provided by applicant): The global HIV/AIDS pandemic is in its 30th year, yet infection rates remain alarmingly high, with 2.6 million people worldwide having become infected in 2009. These troubling statistics highlight the need for efficacious antiretroviral chemoprophylaxis as a preventative measure for at-risk populations. Two large-scale clinical trials recently have shown that pre-exposure prophylaxis (PrEP) prevents infection in a significant proportion of individuals. The CAPRISA 004 trial showed that HIV-susceptible women who adhered to a regimen involving the application of 1% tenofovir vaginal gel prior to intercourse achieved a 54% reduction in HIV transmission. In the iPrEx trial, men and transgender women who have sex with men receiving once-daily emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF) achieved a 44% reduction in HIV acquisition. These highly encouraging results provide a clear rationale for future clinical studies based on systemic and topical PrEP, likely using a combination of antiretroviral agents such as TDF and FTC. In preparation for these trials, the NIAID has identified the development of novel ex vivo systems for the evaluation of antiretroviral agents as a key priority area. Antiretroviral drugs have unpredictable pharmacokinetic (PK) properties involving extensive drug metabolism and transport by membrane-associated carrier proteins. Combination drug therapy often introduces complex drug-drug interactions that can result in toxic or sub-therapeutic drug concentrations and compromise treatment. The objective of this application is to establish cell culture models that faithfully recreate the membrane drug transport processes in the vaginal epithelium and to use these systems to study the transcellular transport of the TDF-FTC drug combination ex vivo. The permeability of biological membranes is one of the most important determinants of a drug's PK profile. Drugs pass through cells by a combination of passive transcellular and carrier-mediated processes. Given the paucity of knowledge on the expression of molecular transporters in the genital tract of humans and animal models, representative ex vivo studies predictive of in vivo PK currently are not possible. We propose to address this urgent need through the following three research phases: (1) Measure baseline gene expression of molecular transporters (membrane proteins) in vaginal tissue from humans and animal models used in the evaluation of topical microbicide formulations; (2) Develop an ex vivo model and apply it to the TDF-FTC combination through the creation of novel, and the utilization of existing, vaginal cell culture systems; and (3) Evaluate ex vivo model predictions by conducting in vivo PK studies using intravaginal rings delivering TDF and FTC topically to the genital tract.