Womp, womp: Effectiveness of Merck’s Thor-inspired COVID pill crashes, upsetting experts

A Merck sign stands in front of the company building on October 2, 2013, in Summit, New Jersey.
Enlarge / A Merck sign stands in front of the company building on October 2, 2013, in Summit, New Jersey.

In a 13-10 vote, Food and Drug Administration advisers narrowly backed the authorization of Merck’s Thor-inspired antiviral pill, molnupiravir, for use against severe COVID-19.

FDA’s group of advisers, the Antimicrobial Drug Advisory Committee (AMDAC), has struggled to a meeting all day Tuesday to weigh the risks of the drug, its modest benefits and the limited data available. The latest analysis suggests that the pill is only 30% effective in preventing hospitalization and death from COVID-19 in people at high risk of serious illness. Meanwhile, the drug has the worrying potential to induce mutations, leading counselors to question whether it should be offered to pregnant women.

The final molnupiravir data and today’s vote are a major disappointment to the initial fanfare around the drug, which initially promised to be an easy-to-use oral drug to effectively prevent severe COVID-19. “Our prediction from our in vitro studies and now with these data is that molnupiravir is named after the correct [thing]… it’s a blow to SARS-CoV-2 regardless of the variant, “said Dean Li, head of research and development at Merck last month.

At the time, Merck and its partner, Ridgeback Biotherapeutics, issued a press release announcing that the antiviral pill appeared to reduce the risk of hospitalization and death from COVID-19 by about 50% in those infected at risk. serious illness. The result came from an interim analysis involving 762 people who were followed for about a month after testing positive. In the placebo group, Merck reported that 53 of 377 people were hospitalized with COVID-19 and eight died. Of the 386 people who received the drug, only 28 were hospitalized and none of these patients died. Comparing the two groups, the rate of hospitalization and death in the placebo group was 14.1 percent compared to only 7.3 percent in the molnupiravir group.

But since this analysis, Merck has collected data from an additional 646 people and in that batch of people the benefit of molnupiravir has disappeared. Of 322 people in the placebo group, 15 were hospitalized and one died. That is, the hospitalization and death rate was about 4.7 percent with a placebo. Of 324 people who received molnupiravir, 20 were hospitalized and one died. That’s a 6.2 percent hospitalization and death rate, which is slightly higher than the rate in the placebo group.

Difficult decisions

For the final analysis, Merck combined the two batches, concluding that molnupiravir was overall 30 percent effective in preventing hospitalizations and deaths. Of the total 699 people who received a placebo, 68 were hospitalized and nine died. Of the total 710 people who received molnupiravir, 48 were hospitalized and one died. Hospitalization and death rates reached 9.7% in the placebo group versus 6.8% in the molnupiravir group, suggesting that the drug resulted in a 3% decrease in absolute risk and a 30% decrease in risk. relative.

Members of the FDA panel summed up the efficacy data as “not extremely good” and “modest at best.”

While there were no safety concerns in either batch of test data, FDA reviewers were distraught with unknowns regarding the drug’s possible mutagenic effects. Molnupiravir works to sabotage SARS-CoV-2 by acting as a basic decoy for the virus’s genetic code. But, with this strategy, there is also the potential that it could disrupt the genetic code of humans. AMDAC members widely felt that Merck had not performed enough safety oversight to better understand the risk of mutations in humans, especially in pregnant women.

Ultimately, the committee was divided by the urgent need for new drugs to reduce deaths from COVID-19 and the fringe and risk benefits that this particular drug offers. In closing remarks, many councilors said their final vote was a difficult decision and asked for more data. Some who voted yes described narrow scenarios in which they could support the use of the drug, namely in very high-risk, non-pregnant and unvaccinated people who understand the risks of the drug and would make sure to take it as indicated.

Following the close vote and many expressions of concern, the FDA will now decide whether to issue an emergency use authorization for molnupiravir. The regulator tends to follow the advice of its advisory committees.

In addition to molnupiravir, the FDA will also be looking at an antiviral pill from Pfizer, which the company says is 89% effective against hospitalizations and deaths from COVID-19. Pfizer noted that its drug carries no risk of mutation.


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