What is the drug and how does it work? Professor Sir Martin Landray, joint chief investigator on the study, explains
An antibody treatment given to Donald Trump last year has been shown to cut deaths in coronavirus patients, offering a new lifeline to people who get severely ill from Covid-19, researchers have said.
The Recovery trial found that REGN-COV, developed by Regeneron, reduced the risk of death when given to patients with severe Covid and who had not been able to mount a natural antibody response on their own.
For every 100 such patients treated with the antibody combination, there would be six fewer deaths, researchers say.
The chances of these patients needing to be put on a ventilator were also reduced, as was the duration of their hospital stay.
A large UK trial involving nearly 10,000 patients between September and May this year saw the patients randomly allocated to receive usual care plus the antibody combination treatment, or usual care alone.
Of these, about one third were seronegative, meaning they had no natural antibody response of their own, and half were seropositive, meaning they had already developed natural antibodies against the virus.
For one sixth of those involved in the study, their serostatus was unknown.
'This is the first time we've found that a drug that's bad for the virus is also really good for the patient'
Researchers found that among patients who received usual care alone, 28-day mortality was twice as high in those without an antibody response (30%) compared with those who were seropositive (15%) at the start of the study.
According to the study, for patients who had no antibody response the treatment reduced the chance of them dying within 28 days by a fifth, compared with usual care alone.
Sir Martin Landray, professor of medicine and epidemiology at the Nuffield Department of Population Health, University of Oxford, and joint chief investigator, told ITV News the treatment is "incredibly important."
"For the sickest patients, when they get into hospital, we've found treatments which can suppress the inflammation that the virus causes. But we haven't found treatments that tackles the virus itself and which then go on to save lives.
"What we've found [with this result] is that among the group of patients who are not making their own antibodies, giving them manufactured antibodies, we can reduce the risk of dying by about a fifth of those patients.
"It's an incredibly important result. The first time we've found that a drug that's bad for the virus is also really good for the patient and I think that will really change the way that we think about tackling this horrible disease as we work forward."
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For the seronegative patients given the treatment, the duration of hospital stay was four days shorter than the usual care group, and the proportion of patients discharged alive by day 28 was greater (64% vs 58%).
The treatment made no difference in patients who had mounted their own antibody response by the time the study started, researchers found.
Sir Peter Horby, professor of emerging infectious diseases in the Nuffield Department of Medicine, University of Oxford, and joint chief investigator for the Recovery trial, said: “These results are very exciting.
“The hope was that by giving a combination of antibodies targeting the Sars-CoV-2 virus we would be able to reduce the worst manifestations of Covid-19.
“There was, however, great uncertainty about the value of antiviral therapies in late-stage Covid-19 disease.
“It is wonderful to learn that even in advanced Covid-19 disease, targeting the virus can reduce mortality in patients who have failed to mount an antibody response of their own.”
Researchers say they are not sure when the treatment will be approved for use in the UK, and highlight it will not be a quick rollout as the drug is not particularly easy to get hold of, and patients would need antibody testing on their admission to hospital – which is not currently in place.
The study will be published as a pre-print on medRxiv and submitted to a journal for peer-review.
The treatment uses a combination of two monoclonal antibodies (casirivimab and imdevimab, known as REGEN-COV in the US) that bind specifically to two different sites on the coronavirus spike protein, neutralising the ability of the virus to infect cells.
Previous studies in patients in the community showed that the treatment reduced viral load, shortened the time to resolution of symptoms, and significantly reduced the risk of being admitted to hospital or death.