Department of Virology, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, USA.
Computer-Assisted Drug Design, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, USA.
Nature. 2015 Nov 12;527(7577):245-8. doi: 10.1038/nature15711. Epub 2015 Nov 4.
It is estimated that more than 170 million people are infected with hepatitis C virus (HCV) worldwide. Clinical trials have demonstrated that, for the first time in human history, the potential exists to eradicate a chronic viral disease using combination therapies that contain only direct-acting antiviral agents. HCV non-structural protein 5A (NS5A) is a multifunctional protein required for several stages of the virus replication cycle. NS5A replication complex inhibitors, exemplified by daclatasvir (DCV; also known as BMS-790052 and Daklinza), belong to the most potent class of direct-acting anti-HCV agents described so far, with in vitro activity in the picomolar (pM) to low nanomolar (nM) range. The potency observed in vitro has translated into clinical efficacy, with HCV RNA declining by ~3-4 log10 in infected patients after administration of single oral doses of DCV. Understanding the exceptional potency of DCV was a key objective of this study. Here we show that although DCV and an NS5A inhibitor analogue (Syn-395) are inactive against certain NS5A resistance variants, combinations of the pair enhance DCV potency by >1,000-fold, restoring activity to the pM range. This synergistic effect was validated in vivo using an HCV-infected chimaeric mouse model. The cooperative interaction of a pair of compounds suggests that NS5A protein molecules communicate with each other: one inhibitor binds to resistant NS5A, causing a conformational change that is transmitted to adjacent NS5As, resensitizing resistant NS5A so that the second inhibitor can act to restore inhibition. This unprecedented synergistic anti-HCV activity also enhances the resistance barrier of DCV, providing additional options for HCV combination therapy and new insight into the role of NS5A in the HCV replication cycle.
据估计，全球有超过 1.7 亿人感染丙型肝炎病毒（HCV）。临床试验表明，人类历史上首次有可能通过仅包含直接作用抗病毒药物的联合疗法根除慢性病毒疾病。丙型肝炎非结构蛋白 5A（NS5A）是一种多功能蛋白，是病毒复制周期的几个阶段所必需的。NS5A 复制复合物抑制剂，以达卡他韦（DCV；也称为 BMS-790052 和 Daklinza）为代表，属于迄今为止描述的最有效的直接作用抗 HCV 药物类别之一，在皮摩尔（pM）至低纳摩尔（nM）范围内具有体外活性。在体外观察到的效力转化为临床疗效，在感染患者中，单次口服给予 DCV 后，HCV RNA 下降约 3-4 个对数 10。了解 DCV 的特殊效力是这项研究的关键目标。在这里，我们表明，尽管 DCV 和 NS5A 抑制剂类似物（Syn-395）对某些 NS5A 耐药变体无活性，但这对化合物的组合将 DCV 的效力提高了>1000 倍，使其恢复到 pM 范围。使用 HCV 感染的嵌合小鼠模型在体内验证了这种协同作用。一对化合物的合作相互作用表明 NS5A 蛋白分子相互通信：一种抑制剂与耐药 NS5A 结合，引起构象变化，传递到相邻的 NS5A 上，使耐药 NS5A 重新敏感，使第二种抑制剂可以作用以恢复抑制。这种前所未有的协同抗 HCV 活性还增强了 DCV 的耐药屏障，为 HCV 联合治疗提供了更多选择，并为 NS5A 在 HCV 复制周期中的作用提供了新的见解。
