Ground-breaking COVID antibody treatment proven to save lives
Results from Regeneron’s Recovery trial, investigating a potent monoclonal antibody combination treatment in hospitalised patients with severe COVID-19, have shown a significant reduction in risk of death, prolonged hospitalisation, and the need for a ventilator.
In the trial, 9785 patients hospitalised with COVID-19 were randomly allocated to receive usual care plus the antibody combination treatment (casirivimab 4g with imdevimab 4g by intravenous infusion) or usual care alone.
Out of the participants, one third were seronegative at baseline (they had not mounted a natural antibody response of their own), one half were seropositive (they had already developed natural antibodies), and one sixth had unknown serostatus.
Data from the study show that among patients who received usual care alone, 28-day mortality was twice as high in those who were seronegative (30%) versus those who were seropositive (15%) at study entry.
Among patients who were seronegative at baseline (the primary analysis population for this comparison), the antibody combination significantly reduced the primary outcome of 28-day mortality by one-fifth compared with usual care alone. This means that for every 100 patients treated with the antibody combination, there would be six fewer deaths.
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.”
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. The trial was the first of a large enough scale to determine definitively whether this treatment reduces mortality in patients hospitalised with severe COVID-19.
There was clear evidence from the trial that the effect of treatment in seronegative patients differed from that in seropositive patients. When combining the larger seropositive group (as well as those with unknown status) with the seronegative patients, there was no longer a significant effect on 28-day mortality.
Only those who have not already made any antibodies of their own to fight the virus should be given the treatment, which costs between £1,000 and £2,000.
Fiona Watt, Executive Chair, Medical Research Council, said: “This is a very important finding. It means that patients being hospitalised with COVID-19 can be divided into two groups based on whether or not they have made antibodies to the virus.
“If they do not have antibodies then treatment with antibody-based drugs to the spike protein can reduce their risk of death and also time spent in hospital. Patients who have made their own antibodies to the virus do not benefit from the new treatment, which is important information given the cost of drugs.”
Kimberley Featherstone, 37, who received the treatment during the trial, said: “I feel very lucky that the trial was up and running by the time I was taken to hospital with Covid-19 and I was able to receive this ground-breaking treatment.
“I’m happy that by participating I played a part in finding out this treatment is successful.”
The preliminary results of the evaluation of the monoclonal antibody combination will be available as a pre-print on medRxiv on 16 June and will be submitted to a leading peer-reviewed medical journal.
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