FDA advisory panel narrowly endorses Merck's oral Covid treatment pill, despite reduced efficacy and safety questions - CNBC

A Food and Drug Administration advisory panel on Tuesday narrowly endorsed the use of Merck and Ridgeback Biotherapeutics' oral Covid treatment pill, despite questions about the drug's effectiveness, safety and whether it would help the virus mutate into even more dangerous variants.

The FDA's Antimicrobial Drugs Advisory Committee voted 13 to 10 to recommend emergency authorization of molnupiravir, an oral antiviral drug initially hailed as a potential game changer in the battle against Covid since it can be taken at home instead of at a hospital like other treatments.

Many members of the advisory committee described the vote as a difficult one, in which they had to carefully weight the risks and benefits of a drug that could help those most at risk but raised many unanswered questions.

Merck originally said the drug was more than 50% effective in preventing hospitalizations and death, but a more full set of data presented to the FDA on Tuesday noted the drug is just 30% effective.

Patrick Harrington, the FDA's senior virology reviewer, said its unclear whether changes in the the spike protein associated with molnupiravir could substantially impact the evolution of the virus more broadly.

Pfizer is similarly seeking approval for its own oral Covid treatment pill that it said was 89% effective in preventing hospitalization and death when administered with a popular HIV drug.

Merck, in its initial application and presentation to the FDA advisory committee on Tuesday, said the pill was 50% effective at reducing the risk of hospitalization or death in an interim analysis of 762 patients.

In a post-interim analysis of 646 participants, hospitalization and deaths were actually higher in the group that took the pill, at 6.2%, compared with those in the placebo group who didn't take the drug, at 4.2%.

"However, there were also more women in the second part of the study, and that's been associated with what we can see with less risk, as well as more patients who were antibody positive," he said.

Kartsonis told the FDA advisory committee that based on the interim analysis of 762 participants, molnupiravir significantly reduced the risk of hospitalization or death during the clinical trial, with nine out of 10 deaths occurring in the placebo group, which didn't receive the medication.

Merck did not identify any safety concerns associated with molnupiravir during the clinical trial, according to Kartsonis.

FDA scientists, in a briefing prepared for the committee, said animal studies found that the drug can result in reduced fetal body weight and abnormal bone formation?

Janet Cragin, a medical officer at the CDC's birth defects division, said it wouldn't be ethical to prescribe molnupiravir during pregnancy given the potential side effects, but denying the drug to a pregnant woman suffering from Covid is also problematic.

"Pregnancy itself can be considered a risk factor for progression to severe Covid illness," she said.

Robert Heflich, director of the FDA's genetic and molecular toxicology division, said the risk of molnupiravir altering human genes in a clinical setting is low, given that the drug clearly was not mutagenic during a study in rodents