BACKGROUND & AIMS The hallmarks of chronic HBV infection are a high viral load (HBV DNA) and even higher levels (>100-fold in excess of virions) of non-infectious membranous particles containing the tolerogenic viral S antigen (HBsAg). Currently, standard treatment effectively reduces viremia but only rarely results in a functional cure (defined as sustained HBsAg loss). There is an urgent need to identify novel therapies that reduce HBsAg levels and restore virus-specific immune responsiveness in patients. We report the discovery of a novel, potent and orally bioavailable small molecule inhibitor of HBV gene expression (RG7834). METHODS RG7834 antiviral characteristics and selectivity against HBV were evaluated in HBV natural infection assays and in a urokinase-type plasminogen activator/severe combined immunodeficiency humanized mouse model of HBV infection, either alone or in combination with entecavir. RESULTS Unlike nucleos(t)ide therapies, which reduce viremia but do not lead to an effective reduction in HBV antigen expression, RG7834 significantly reduced the levels of viral proteins (including HBsAg), as well as lowering viremia. Consistent with its proposed mechanism of action, time course RNA-seq analysis revealed a fast and selective reduction in HBV mRNAs in response to RG7834 treatment. Furthermore, oral treatment of HBV-infected humanized mice with RG7834 led to a mean HBsAg reduction of 1.09 log10 compared to entecavir, which had no significant effect on HBsAg levels. Combination of RG7834, entecavir and pegylated interferon α-2a led to significant reductions of both HBV DNA and HBsAg levels in humanized mice. CONCLUSION We have identified a novel oral HBV viral gene expression inhibitor that blocks viral antigen and virion production, that is highly selective for HBV, and has a unique antiviral profile that is clearly differentiated from nucleos(t)ide analogues. LAY SUMMARY We discovered a novel small molecule viral expression inhibitor that is highly selective for HBV and unlike current therapy inhibits the expression of viral proteins by specifically reducing HBV mRNAs. RG7834 can therefore potentially provide anti-HBV benefits and increase HBV cure rates, by direct reduction of viral agents needed to complete the viral life cycle, as well as a reduction of viral agents involved in evasion of the host immune responses.

中文翻译：

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一种抑制乙型肝炎病毒表达的新型口服小分子

背景和目的 慢性 HBV 感染的标志是高病毒载量 (HBV DNA) 和更高水平（超过病毒粒子的 100 倍）含有致耐受性病毒 S 抗原 (HBsAg) 的非感染性膜颗粒。目前，标准治疗可有效减少病毒血症，但很少导致功能性治愈（定义为 HBsAg 持续消失）。迫切需要确定降低 HBsAg 水平并恢复患者病毒特异性免疫反应的新疗法。我们报告发现了一种新型的、有效的、口服生物可利用的 HBV 基因表达小分子抑制剂 (RG7834)。方法 RG7834 的抗病毒特性和对 HBV 的选择性在 HBV 自然感染试验和尿激酶型纤溶酶原激活剂/HBV 感染的严重联合免疫缺陷人源化小鼠模型中进行评估，单独或与恩替卡韦联合使用。结果 与减少病毒血症但不会导致 HBV 抗原表达有效减少的核苷（酸）疗法不同，RG7834 显着降低了病毒蛋白（包括 HBsAg）的水平，并降低了病毒血症。与其提出的作用机制一致，时程 RNA-seq 分析揭示了响应 RG7834 治疗的 HBV mRNA 的快速和选择性减少。此外，与恩替卡韦相比，用 RG7834 口服治疗 HBV 感染的人源化小鼠导致 HBsAg 平均降低 1.09 log10，对 HBsAg 水平没有显着影响。RG7834、恩替卡韦和聚乙二醇化干扰素 α-2a 的组合导致人源化小鼠的 HBV DNA 和 HBsAg 水平显着降低。结论 我们已鉴定出一种新型口服 HBV 病毒基因表达抑制剂，可阻断病毒抗原和病毒粒子的产生，对 HBV 具有高度选择性，并具有独特的抗病毒特性，与核苷（酸）类似物明显不同。概述我们发现了一种新的小分子病毒表达抑制剂，它对 HBV 具有高度选择性，并且与目前的疗法不同，它通过特异性减少 HBV mRNA 来抑制病毒蛋白的表达。因此，通过直接减少完成病毒生命周期所需的病毒因子，RG7834 可以潜在地提供抗 HBV 益处并提高 HBV 治愈率，