Pfizer seeks FDA approval for Covid drug in high-risk patients

Pfizer Inc. asked US regulators for full approval of Paxlovid, its Covid-19 drug that’s now used on an emergency basis, for people at high risk of developing severe disease.

Submission of a new drug application to the US Food and Drug Administration brings the New York drugmaker a step closer to securing a formal clearance that would allow it to sell and market the product outside the pandemic emergency. Pfizer is seeking approval for use in both vaccinated and nonvaccinated people.

Shares of Pfizer rose 1.8% on Thursday at the New York open.

An oral antiviral treatment for people with mild to moderate Covid, Paxlovid is intended to prevent death and hospitalization in people most at risk, such as the elderly and those with underlying health conditions. 

Pfizer suggested that the market for its product is large, citing Centers for Disease Control and Prevention data showing that 60% of the US population is estimated to have at least one risk factor for progressing to severe Covid illness.

The drugmaker has faced setbacks in efforts to reach an even broader population. Earlier this month, Pfizer stopped enrollment in a study of the drug in patients who weren’t at high risk of severe disease after the pill didn’t alleviate symptoms.

The study failed to demonstrate that the drug reduced Covid symptoms among relatively healthy patients and wasn’t able to show a statistically significant reduction in hospitalization and death. 

Paxlovid has also faced questions about the return of symptoms among scores of patients who’ve received the drug. 

Anthony Fauci, President Joe Biden’s top medical adviser, suffered Covid rebound after taking Paxlovid, and said he felt better after starting a second course, a strategy that had been suggested earlier by Pfizer Chief Executive Officer Albert Bourla. 

The FDA has said there’s no evidence showing that a second course of the treatment helps people whose symptoms resume. 

Researchers are also warning of possible viral resistance to Paxlovid if the drug continues to be used widely, calling for close monitoring of resistance-related mutations in a study published Tuesday on a preprint server. 

Such mutations have already been seen in some versions of the virus, according to the study from researchers at Rutgers University, the University of South Florida and the Catholic University of America. The research hasn’t undergone vetting by outside scientists. 

Several academics and research groups have called for study of combinations of Paxlovid with other drugs as a tool to thwart potential resistance.