Discovery of orally bioavailable SARS-CoV-2 papain-like protease inhibitor as a potential treatment for COVID-19

Abstract

AbstractThe RNA-dependent RNA polymerase (RdRp), 3C-like protease (3CLpro), and papain-like protease (PLpro) are pivotal components in the viral life cycle of SARS-CoV-2, presenting as promising therapeutic targets. Currently, all FDA-approved antiviral drugs against SARS-CoV-2 are RdRp or 3CLproinhibitors. However, the mutations causing drug resistance have been observed in RdRp and 3CLprofrom SARS-CoV-2, which makes it necessary to develop antivirals with novel mechanisms. Through the application of a structure-based drug design (SBDD) approach, we discovered a series of novel potent non-covalent PLproinhibitors with remarkablein vitropotency andin vivoPK properties. The co-crystal structures of PLprowith leads revealed that the residues D164 and Q269 around the S2 site are critical for improving the inhibitor’s potency. The lead compound GZNL-P36 not only inhibited SARS-CoV-2 and its variants at the cellular level with EC50 ranging from 58.2 nM to 306.2 nM, but also inhibited HCoV-NL63 and HCoV-229E with EC50 of 81.6 nM and 2.66 μM, respectively. Oral administration of the compound resulted in significantly improved survival and notable reductions in lung viral loads and lesions in SARS- CoV-2 infection mouse model, consistent with RNA-seq data analysis. Our results indicate that PLproinhibitor is a promising SARS-CoV-2 therapy.