Pfizer wasn’t the only drugmaker to score an early Christmas present from the FDA this year. A day after Paxlovid’s blessing as the first oral COVID-19 treatment, Merck & Co. and Ridgeback Biotherapuetics’ molnupiravir entered the fray as the second antiviral pill authorized in the U.S.
Late last week, the FDA endorsed molnupiravir to treat adults with mild-to-moderate COVID-19, with an emergency authorization specifically aimed at patients with a high risk of progressing to severe cases of the pandemic disease, including hospitalization or death. The agency's green light also includes patients for whom other authorized COVID-19 treatments “are not accessible or clinically appropriate,” the FDA said in a release.
The approval comes at the “right time,” Cantor Fitzgerald analyst Louise Chen wrote in a recent note to clients. More therapeutics are needed to supplement vaccinations, especially in light of troubling variants like omicron.
Molnupiravir may not see as much widespread use compared to Pfizer's oral antiviral Paxlovid, however, which Chen's team attributes to the latter's superior profile of safety and efficacy. Nevertheless, molnupiravir’s go-ahead is “good news” for Merck, and both drugs will likely be used to help “flatten the curve,” Chen said.
The FDA’s emergency nod comes with a list of caveats. First, patients should start on the antiviral “as soon as possible” after a COVID-19 diagnosis, and at most within five days of symptoms starting. The drug isn’t cleared for pre- or post-exposure prevention nor for initiation of treatment in hospitalized patients, since the drug’s benefit hasn’t been seen in that group.
The antiviral cannot be used in patients younger than 18 because it may affect bone and cartilage growth, the FDA said. People who are pregnant shouldn’t take molnupiravir, either: Animal reproduction studies suggest the antiviral may cause fetal harm.
Molnupiravir works by introducing errors into the SARS-CoV-2 virus’s genetic code, which in turn stops the virus from replicating. The drug is only authorized for use over five days. Patients on the drug receive four 200-mg capsules every 12 hours, for a total of 40 capsules over the five-day stretch.
The FDA issued its blessing on an interim analysis from the late-stage MOVe-OUT trial, which pitted molnupiravir against placebo in non-hospitalized patients who were unvaccinated against COVID-19. Patients needed to have a laboratory-confirmed COVID-19 infection, their symptoms needed to start within five days of randomization, and they needed to have at least one risk factor linked to poor disease outcomes, such as heart disease or diabetes, Merck said in a release.
With a pool of 762 patients, the interim analysis showed that molnupiravir “significantly” slashed the risk of hospitalizations and death through day 29 of the study. Among the molnupiravir group, 7.3% of patients were hospitalized or died, versus 14.1% in the placebo arm.
Looking beyond the interim analysis, 9.7% of people on placebo were hospitalized or died, compared to 6.8% in the molnupiravir cohort. In total, there were nine deaths in the placebo group versus one in the molnupiravir arm.
“Because we recognized the promise of molnupiravir early, Merck invested at risk and we are executing an unprecedented global access strategy so that molnupiravir, now authorized, can be available to patients here in the U.S. and all around the world more quickly and more equitably than has ever been accomplished before,” Merck CEO Robert Davis said in a statement.
The New Jersey-based drugmaker on Thursday said it planned to start shipping molnupiravir to the pharma distributor AmerisourceBergen “within days.” Merck currently has a $2.2 billion deal with the U.S. government to provide some 3.1 million courses of the drug.
Indeed, global access has been a “priority” for Merck and Ridgeback since the start of their team-up. They’re also leveraging tiered pricing based on the ability of governments to finance healthcare. Perhaps most critically, Merck and Ridgeback have forged licensing pacts with certain generic manufacturers and the Medicines Patent Pool to get generic molnupiravir on tap in more than 100 low- and middle-income countries.
Merck expects to produce 10 million courses of the drug by the end of the year, with plans to deliver at least 20 million courses in 2022. Outside the U.S., Merck and Ridgeback have pledged to supply their drug to more than 30 countries including Australia, Canada, Korea, Japan, Thailand and the U.K.