US health panel endorses Merck’s COVID-19 pill

A panel of US health experts has voted to recommend Merck’s antiviral pill to treat COVID-19.

The independent scientists appointed by the Food and Drug Administration (FDA) voted on Tuesday 13 in favour and 10 against its authorisation.

A narrow win reflected some concerns over a recent downgrading of the treatment’s efficacy results, as well as misgivings over potential side effects.

“I see this as an incredibly difficult decision with many more questions than answers,” said panel chair Dr Lindsey Baden of the Harvard Medical School, who voted in favour of the medication.

He said FDA would have to carefully tailor the drug’s use for patients who stand to benefit most.

If the FDA authorises the drug, it would be the first at-home treatment for the virus nearly two years into the pandemic.

The authorisation would likely be limited to patients at high risk of developing severe disease, although the exact population would be defined by the agency.

Molnupiravir, already authorised in Britain, has been shown to reduce the rate of hospitalisations and deaths among people at high risk of developing severe COVID-19 when it is taken within five days of the onset of symptoms.

Clinical trial results

The FDA is expected to grant an emergency use authorisation (EUA) for the treatment, meaning millions of courses will soon be stocked in pharmacies.

Last week, Merck, known as MSD outside the United States and Canada, released full results from a clinical trial of 1,400 people.

It was found to be safe in its clinical trial, with non-serious adverse events such as diarrhoea and dizziness occurring roughly equally between the placebo group and the drug group.

The research showed the pill reduced the risk of hospitalisations and death by 30 percent, a significant result albeit more modest than an earlier advertised figure of 50 percent, which was based on an analysis from half the number of patients.

Merck has not specifically tested its drug against the new variant but said it should have some potency based on its effectiveness against other strains of coronavirus.

That uncertainty frustrated many panellists as they grappled with whether to back the treatment for millions of Americans.

“With no data saying it works with new variants, I really think we need to be careful about saying that this is the way to go,” said Dr David Hardy of Charles Drew University School of Medicine and Science, who ultimately voted to back the drug.

Benefit-risk balance

Briefing documents uploaded by the FDA ahead of the meeting illustrated the benefit-risk balance the experts were asked to assess.

Tuesday’s vote specifically backed the drug for adults with mild-to-moderate COVID-19 who face the greatest risks, including older people and those with conditions like obesity and asthma.

Potential harmful effects were noted on foetal development, as seen in studies on rats and rabbits, and Merck said it would not recommend the use of molnupiravir in pregnant women.

Most experts also said the drug should not be used in vaccinated people, who were not part of Merck’s research and have not been shown to benefit.

The company did not seek authorisation for children, and the FDA said it did not plan to carry out pediatric trials until safety is established in juvenile rats over concerns related to bone formation.

Currently, the most effective treatment for COVID-19 is monoclonal antibodies, which are administered via a drip and have been shown to reduce the risk of severe cases in high-risk patients by up to 70 percent.

But pills have the advantage of being far easier to use, and, unlike antibodies, do not require a visit to an infusion site.

Molnupiravir, which was developed in partnership with Ridgeback Biotherapeutics, works by introducing mutations into the genetic material of the coronavirus, inhibiting its ability to replicate.

The treatment is taken as four capsules, twice a day, over five days in a total of 40 pills.

It is thought likely to be more variant-proof than monoclonal antibodies or vaccines because unlike them, it does not go after the ever-mutating spike proteins that dot the surface of the virus.

The US government has committed to buying 3.1 million courses of molnupiravir for approximately $2.2bn, with the option to buy more.