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

描述(申请人提供)：丙型肝炎病毒(丙型肝炎病毒)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)。虽然使用聚乙二醇化干扰素-α(PEGylated Interferon-Alpha，PEG-干扰素)加利巴韦林(Ribavirin，RBV)治疗可使40%-50%的患者出现持续的病毒学应答(SVR)，但在非洲裔美国人和拉美裔美国人中，SVR的发生率仅为20%左右，他们的单核苷酸多态频率较高，且应答较差(4，5)。加入针对丙型肝炎病毒NS3/4A蛋白酶的直接作用抗病毒药物(DAA)可将先前未治疗的患者的SVR率提高到68-75%，但此类方案仍受到聚乙二醇-干扰素/RBV的限制。因此，药物开发商正在寻找DAA的组合，以减少或消除对聚乙二醇-干扰素和/或RBV的需求，同时提供足够的耐药性屏障。最近有报道称，在以NS3/4A和NS5A为靶点的两种DAA联合治疗后，少数1a和1b型患者实现了SVR。虽然这些结果为不使用聚乙二醇-干扰素/RBV的SVR提供了概念证据，但为选择这种DAA组合提供信息的生物学数据是有限的。在Huh-7肝癌细胞系中，利用亚基因组丙型肝炎病毒复制子，获得了DAA及其组合的临床前特征的优势，这是一个省略病毒生命周期重要特征的重组系统。已经开发出了在肝癌细胞系和原代人肝细胞/肝母细胞中概括完整的丙型肝炎病毒生命周期的系统。这项研究建议询问DAA在支持完整的丙型肝炎病毒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.