EU starts review of Merck's oral COVID drug molnupiravir

The EMA has started a rolling review of Merck & Co and Ridgeback Biotherapeutics' much-anticipated oral antiviral molnupiravir as a treatment for COVID-19 in adults.

Molnupiravir is already filed for approval in the US and Canada – where Merck is known as MSD – amid hopes that the drug could be used to protect vulnerable people with mild or moderate COVID-19 from developing severe disease with a drug that can be delivered outside the hospital.

All three filings come within a few weeks of Merck and Ridgeback reporting the results of the MOVe-OUT trial, which revealed a significant 50% reduced risk of hospitalisation or death in these patients compared to placebo with the drug, cutting the rate to 7% from 14%.

The trial tested an 800mg twice-daily dose of molnupiravir in older people and subjects with other health problems like obesity, diabetes and heart disease that make the risk of COVID-19 complications greater.

The EMA said the clinical and non-clinical results to date suggest that the medicine may reduce the ability of SARS-CoV-2 to multiply in the body, thereby preventing hospitalisation or death. If approved, it will be the first oral antiviral for COVID-19.

Current treatment options include Gilead Sciences' antiviral infusion Veklury (remdesivir) and the generic steroid dexamethasone, but these are both used for patients with more severe COVID-19 in hospital.

Antibody therapies meanwhile have been developed for non-hospitalised patients, but these still have to be administered by infusion in a clinic. An oral drug that can be administered in the community could help keep patients out of hospital and alleviate pressure on healthcare systems.

One issue likely to feature in the regulatory reviews of molnupiravir is that drugs in the same polymerase inhibitor class have been linked to birth defects in animal studies. Merck says however that its studies indicate that the drug does not affect mammalian DNA.

The drugmaker has already sold 1.7 million treatment courses to the US government in a deal valued at $1.2 billion that equates to a price of around $700 per course, and says other supply deals are being negotiated.

Last week, the UK said it had secured 480,000 doses of molnupiravir, along with 250,00 courses of another antiviral medicine developed by Pfizer that is based on new compound PF-07321332 and a low dose of HIV drug ritonavir. Pfizer's drug is currently in late-stage clinical trials.

The UK government said the drugs are expected to be given to those most at risk from COVID-19 to "reduce the severity of symptoms and ease pressure on the NHS over winter."

Merck has said it expects to be able to supply more than 10 million courses of the antiviral by the end of the year if molnupiravir gets approved.