Pfizer Inc has started an early-stage U.S. trial of an that could be prescribed to patients at the first sign of infection, the company said on Tuesday.
The drugmaker, which developed the first authorized COVID-19 vaccine in the U.S. with Germany's BioNTech SA, said the antiviral candidate showed potent activity against SARS-CoV-2, the virus that causes COVID-19, in lab studies.
Pfizer's candidate, named PF-07321332, is a protease inhibitor that prevents the virus from replicating in cells.
Protease inhibitors have been effective at treating other viral pathogens such as HIV and hepatitis C virus, both on their own and in combination with other antivirals, the company said.
Pfizer believes this class of molecules may provide well-tolerated treatments against COVID-19, as currently marketed therapeutics that work on the same lines have not reported safety concerns.
The company is also studying an intravenously administered antiviral candidate in an early-stage trial in hospitalized COVID-19 patients.
"Together, the two (oral and intravenous candidates) have the potential to create an end-to-end treatment paradigm that complements vaccination in cases where disease still occurs," Pfizer's Chief Medical Officer Mikael Dolsten said in a statement.
Pfizer's candidate is behind two other oral antiviral therapies, which are in mid-stage trials – the first being developed by rival Merck & Co with Ridgeback Bio, and a second from Roche Holding and Atea Pharmaceuticals.
Gilead Sciences' remdesivir is currently the only U.S. Food and Drug Administration-approved drug for the treatment of COVID-19.
The FDA has granted an emergency authorization to intravenous therapies from Eli Lilly - bamlanivimab alone and in combination with etesevimab, and a combination therapy from Regeneron.
Reporting by Vishwadha Chander in Bengaluru; Editing by Shailesh Kuber
