Rapid repurposing of existing drugs as new therapeutics for COVID-19 has been an important strategy in the management of disease severity during the ongoing SARS-CoV-2 pandemic. Here, we used high-throughput docking to screen 6000 compounds within the DrugBank library for their potential to bind and inhibit the SARS-CoV-2 3 CL main protease, a chymotrypsin-like enzyme that is essential for viral replication. For 19 candidate hits, parallel in vitro fluorescence-based protease-inhibition assays and Vero-CCL81 cell-based SARS-CoV-2 replication-inhibition assays were performed. One hit, diclazuril (an investigational anti-protozoal compound), was validated as a SARS-CoV-2 3 CL main protease inhibitor in vitro (IC50 value of 29 µM) and modestly inhibited SARS-CoV-2 replication in Vero-CCL81 cells. Another hit, lenvatinib (approved for use in humans as an anti-cancer treatment), could not be validated as a SARS-CoV-2 3 CL main protease inhibitor in vitro, but serendipitously exhibited a striking functional synergy with the approved nucleoside analogue remdesivir to inhibit SARS-CoV-2 replication, albeit this was specific to Vero-CCL81 cells. Lenvatinib is a broadly-acting host receptor tyrosine kinase (RTK) inhibitor, but the synergistic effect with remdesivir was not observed with other approved RTK inhibitors (such as pazopanib or sunitinib), suggesting that the mechanism-of-action is independent of host RTKs. Furthermore, time-of-addition studies revealed that lenvatinib/remdesivir synergy probably targets SARS-CoV-2 replication subsequent to host-cell entry. Our work shows that combining computational and cellular screening is a means to identify existing drugs with repurposing potential as antiviral compounds. Future studies could be aimed at understanding and optimizing the lenvatinib/remdesivir synergistic mechanism as a therapeutic option.

中文翻译：

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联合计算和细胞筛选确定了乐伐替尼和瑞德西韦对 SARS-CoV-2 的协同抑制作用

在持续的 SARS-CoV-2 大流行期间，快速重新利用现有药物作为 COVID-19 的新疗法一直是管理疾病严重程度的重要策略。在这里，我们使用高通量对接来筛选 DrugBank 库中的 6000 种化合物，以了解它们结合和抑制 SARS-CoV-2 3 CL 主蛋白酶（一种对病毒复制必不可少的类糜蛋白酶）的潜力。对于 19 个候选命中，进行了平行的基于体外荧光的蛋白酶抑制试验和基于 Vero-CCL81 细胞的 SARS-CoV-2 复制抑制试验。地克珠利（一种研究性抗原生动物化合物）在体外被验证为 SARS-CoV-2 3 CL 主要蛋白酶抑制剂（IC 50值 29 µM）并适度抑制 Vero-CCL81 细胞中的 SARS-CoV-2 复制。另一个热门产品乐伐替尼（已获准用于人类抗癌治疗）无法在体外验证为 SARS-CoV-2 3 CL 主要蛋白酶抑制剂，但意外地与批准的核苷类似物瑞德西韦表现出惊人的功能协同作用，以抑制 SARS-CoV-2 复制，尽管这对 Vero-CCL81 细胞具有特异性。乐伐替尼是一种广泛作用的宿主受体酪氨酸激酶 (RTK) 抑制剂，但与其他已批准的 RTK 抑制剂（如帕唑帕尼或舒尼替尼）未观察到与瑞德西韦的协同作用，表明其作用机制与宿主 RTK 无关. 此外，添加时间研究表明，乐伐替尼/瑞德西韦的协同作用可能针对宿主细胞进入后的 SARS-CoV-2 复制。我们的工作表明，结合计算和细胞筛选是一种识别具有再利用潜力作为抗病毒化合物的现有药物的方法。