FDA Panel Reviews Data Showing Merck’s COVID-19 Antiviral Reduces Hospitalization by 30 Percent

Merck’s COVID-19 antiviral, molnupiravir, lowered the risk of hospitalization or death by just 30 percent, according to the results of a late-stage study that will be reviewed today by an FDA expert panel.

The full results from the 1,433-participant phase 3 trial represent a substantial decrease from the nearly 50 percent reduction in risk of hospitalization or death seen in an earlier analysis.

The new data could impact how agency officials assess the drug’s risk/benefit profile, and under what circumstances the expert panel might recommend granting the treatment an Emergency Use Authorization (EUA).

Specifically, the FDA’s Antimicrobial Drugs Advisory Committee will discuss whether molnupiravir should be made available to pregnant women under certain scenarios, whether the drug could increase the rate of mutation of the SARS-CoV-2 virus ― such as the newly identified Omicron variant ― and whether the drug should be authorized for adults with mild-to-moderate COVID-19 at high risk of progressing to severe disease.

On that last question, panelists will vote yes or no and describe which populations they believe should be offered the pill five days following the onset of symptoms.

The FDA’s briefing documents indicate that the agency is uncertain whether vaccinated patients with breakthrough cases should be given the oral pill as it didn’t appear to benefit a trial subgroup with COVID-19 antibodies. The agency also noted there wasn’t enough data to draw conclusions for this population.

Merck and co-developer Ridgeback Biotherapeutics have a lot riding on the advisory committee’s opinion. The U.S. government has agreed to purchase 3.1 million treatment courses of molnupiravir for an estimated $2.2 billion through early next year, but only if the FDA signs off on the drug. Molnupiravir recently won UK authorization, but that’s no guarantee it will also receive the regulatory green light in the U.S. (DID, Nov. 5).

Assuming the drugmakers do snag an FDA emergency authorization for molnupiravir, they will likely face imminent competition from Pfizer’s COVID-19 antiviral Paxlovid (PF-07321332; ritonavir). Pfizer filed an EUA application for Paxlovid earlier this month, after interim phase 2/3 data showed the drug cut the risk of hospitalization and death by 89 percent vs. placebo (DID, Nov. 19). ― Jason Scott