“The oral antiviral clinical candidate PF-07321332, a SARS-CoV2- 3CL protease inhibitor, has demonstrated potent in vitro anti-viral activity against SARS-CoV-2, as well as activity against other coronaviruses, suggesting potential for use in the treatment of Covid as well as potential use to address future coronavirus threats,” Pfizer said in a statement. “This is the first orally administered coronavirus-specific protease inhibitor to be evaluated in clinical studies.” Protease inhibitors bind to a viral enzyme (called a protease), preventing the virus from replicating in the cell. Protease inhibitors have been effective at treating other viral pathogens such as HIV and the Hepatitis C virus, both alone and in combination with other antivirals.
Mikael Dolsten, Pfizer chief scientific officer, said: “We have designed PF-07321332 as a potential oral therapy that could be prescribed at the first sign of infection, without requiring that patients are hospitalised or in critical care.”
A Pfizer spokesperson said, “Given the programme is still in research and development, we cannot speculate on any potential, timeline or outcome.”
Pfizer is also investigating an intravenously administered investigational protease inhibitor, PF-07304814, currently in a Phase 1-b multi-dose trial among hospitalised clinical trial participants with Covid.