Hepatitis C antivirals: Mechanism of action, combination efficacy and resistance

描述（由申请人提供）：丙型肝炎病毒（HCV）是全球慢性肝病的主要原因（1），也是美国肝移植的主要适应症（2，3）。虽然用聚乙二醇化干扰素-α（PEG-IFN）加利巴韦林（RBV）的治疗在总体上40-50%的患者中提供了持续的病毒学应答（SVR），但在非洲裔美国人和西班牙裔美国人中，SVR率仅为约20%，这些人具有与不良应答相关的较高频率的单核苷酸多态性（4，5）。加入靶向HCV NS 3/4A蛋白酶的直接作用抗病毒药物（DAA）使先前未经治疗的患者的SVR率增加至68-75%，但此类方案仍然受到PEG-IFN/RBV的限制。因此，药物开发者正在寻求DAA的组合，其将减少或消除对PEG-IFN和/或RBV的需要，同时提供足够的耐药性屏障。最近有报道称，少数基因型1a和1b的患者在使用靶向NS 3/4A和NS 5A的两种DAA组合治疗后实现了SVR。虽然这些结果为不使用PEG-IFN/RBV的SVR提供了概念证明，但告知选择此类DAA组合的生物学数据是有限的。DAA和组合的临床前表征的优势已经在Huh-7肝癌衍生细胞系中使用亚基因组HCV复制子获得，Huh-7肝癌衍生细胞系是一种省略病毒生命周期的重要特征的重组系统。已经开发了系统，其概括了肝癌细胞系和原代人肝细胞/成肝细胞中的完整HCV生命周期。这项研究提出询问DAA在支持完整HCV生命周期的细胞系统中的作用。这些研究将加深我们对病毒复制所涉及的关键生物学过程的理解，并为DAA的作用机制提供新的见解，这些机制将可转化为临床研究。

DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) is a major cause of chronic liver disease worldwide (1) and is the major indication for liver transplantation in the United States (2, 3). While therapy with PEGylated Interferon-alpha (PEG-IFN) plus ribavirin (RBV) provides sustained virologic response (SVR) in 40-50% of patients overall, the SVR rate is only about 20% in African Americans and Hispanics, who have a higher frequency of single nucleotide polymorphisms associated with poor response (4, 5). Addition of direct-acting antivirals (DAAs) targeting the HCV NS3/4A protease increases SVR rates to 68-75% in previously untreated patients, but such regimens still suffer from the limitations of PEG-IFN/RBV. Thus, drug developers are seeking combinations of DAAs that will reduce or eliminate the need for PEG-IFN and/or RBV while providing an adequate barrier to resistance. It was recently reported that a small number of genotype 1a and 1b patients achieved SVR following treatment with a combination of two DAAs targeting NS3/4A and NS5A. While these results provide proof of concept for SVR without use of PEG-IFN/RBV, biological data to inform the selection of such DAA combinations are limited. The preponderance of preclinical characterization of DAAs and combinations has been obtained using subgenomic HCV replicons in Huh-7 hepatoma-derived cell lines, a recombinant system that omits important features of the viral life cycle. Systems have been developed that recapitulate the complete HCV life cycle in hepatoma lines and primary human hepatocytes/hepatoblasts. This study proposes to interrogate the effects of DAAs in cell systems that support the complete HCV life cycle. These studies will deepen our understanding of key biological processes involved in viral replication and provide new insights into DAA mechanisms of action that will be translatable to clinical studies.