ABSTRACT
The worldwide outbreak of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. Alongside vaccines, antiviral therapeutics are an important part of the healthcare response to countering the ongoing threat presented by COVID-19. Here, we report the discovery and characterization of PF-07321332, an orally bioavailable SARS-CoV-2 main protease inhibitor with in vitro pan-human coronavirus antiviral activity and excellent off-target selectivity and in vivo safety profiles. PF-07321332 has demonstrated oral activity in a mouse-adapted SARS-CoV-2 model and has achieved oral plasma concentrations exceeding the in vitro antiviral cell potency in a phase 1 clinical trial in healthy human participants.
Subject(s)
COVID-19 Drug Treatment , Lactams/pharmacology , Lactams/therapeutic use , Leucine/pharmacology , Leucine/therapeutic use , Nitriles/pharmacology , Nitriles/therapeutic use , Proline/pharmacology , Proline/therapeutic use , SARS-CoV-2/drug effects , Viral Protease Inhibitors/pharmacology , Viral Protease Inhibitors/therapeutic use , Administration, Oral , Animals , COVID-19/virology , Clinical Trials, Phase I as Topic , Coronavirus/drug effects , Disease Models, Animal , Drug Therapy, Combination , Humans , Lactams/administration & dosage , Lactams/pharmacokinetics , Leucine/administration & dosage , Leucine/pharmacokinetics , Mice , Mice, Inbred BALB C , Microbial Sensitivity Tests , Nitriles/administration & dosage , Nitriles/pharmacokinetics , Proline/administration & dosage , Proline/pharmacokinetics , Randomized Controlled Trials as Topic , Ritonavir/administration & dosage , Ritonavir/therapeutic use , SARS-CoV-2/physiology , Viral Protease Inhibitors/administration & dosage , Viral Protease Inhibitors/pharmacokinetics , Virus Replication/drug effectsABSTRACT
The novel coronavirus disease COVID-19 that emerged in 2019 is caused by the virus SARS CoV-2 and named for its close genetic similarity to SARS CoV-1 that caused severe acute respiratory syndrome (SARS) in 2002. Both SARS coronavirus genomes encode two overlapping large polyproteins, which are cleaved at specific sites by a 3C-like cysteine protease (3CLpro) in a post-translational processing step that is critical for coronavirus replication. The 3CLpro sequences for CoV-1 and CoV-2 viruses are 100% identical in the catalytic domain that carries out protein cleavage. A research effort that focused on the discovery of reversible and irreversible ketone-based inhibitors of SARS CoV-1 3CLpro employing ligand-protease structures solved by X-ray crystallography led to the identification of 3 and 4. Preclinical experiments reveal 4 (PF-00835231) as a potent inhibitor of CoV-2 3CLpro with suitable pharmaceutical properties to warrant further development as an intravenous treatment for COVID-19.