A coronavirus treatment made of artificial antibodies reduces the risk of death in the sickest Covid-19 patients by a fifth, an Oxford-led trial has found. 

Regeneron’s monoclonal antibody cocktail was tested on almost 10,000 people in the UK by Recovery, the biggest study in the world looking for coronavirus treatments.

It revealed that people in hospital with Covid who are unable to make their own antibodies, known as seronegative, benefit significantly from the treatment.

A person can fail to produce antibodies for various reasons, often they are elderly and frail; have pre-existing health conditions such as cancer and leukemia; or are already taking immunosuppressive medication. 

Around one third of people in the study failed to make their own antibodies and, without the new treatment, have a 30 per cent chance of dying from Covid. The survival odds are twice as good, on average, for people who can make antibodies.

Participants in the study were given either the usual standard of care from the NHS, which includes dexamethasone, or had this supplemented with the Regeneron product. 

Drop in risk represents ‘six lives saved for every 100’

When seronegative people were given the experimental treatment, the mortality rate dropped from 30 per cent to 24 per cent. 

The six per cent decrease in absolute risk is equivalent to a 20 per cent drop in relative risk which translates into six lives saved for every 100 patients who receive the antibody treatment, the researchers say.

The treatment also reduces the time these patients spend in hospital by four days and the risk of needing to be put on a ventilator was found to drop by 17 per cent. 

But the Regeneron product had no impact, positive or negative, for people who naturally produced their own antibodies following infection.

The treatment is given via a one-off intravenous drip and includes four grams of casirivimab  and four grams of imdevimab which both latch on to different parts of the spike protein protruding from the surface of a SARS-CoV-2 particle. 

A single dose costs in excess of £1,000 and has been shown to work on all current variants of the virus. 

Professor Sir Martin Landrey, Joint Chief Investigator of the Recovery trial, said using two antibodies, not just one, was a “belt and braces” approach to ensure the treatment will be effective against all variants, and any more which emerge in the future. 

Prof Peter Horby says there is no variant that is resistant to both antibodies

Credit: PA

“There’s two antibodies in this particular combination and some of the variants have lost the ability to be neutralised by one of those two antibodies,” said Professor Sir Peter Horby, Joint Chief Investigator of the Recovery trial.

“But there is no variant yet that is resistant to both. In variants that are resistant to one of the components, for example the South Africa variant, you still get full potency because they’re not additive. If one of them works, it works as well as both of them.” 

He added that the delta variant, which is now dominant in the UK, and the UK alpha variant are not resistant and both antibodies work against these strains.

Regeneron, the company which makes the monoclonal antibody treatment, has not yet received authorisation for the product to be used in the UK. 

The treatment received emergency approval in the US last year after Donald Trump claimed it “cured” him after he tested positive for the virus. 

Treatment should be approved ‘in weeks’

Prof Landry hopes that, much like with the vaccine, the approval of this treatment can now be accelerated, and believes it should be approved for use on the NHS “in weeks”. 

“In some ways, this is a first as an approach,” Prof Landry said. “This is an antiviral treatment which is used late on [in a person’s disease] and has a demonstrated, clear impact on survival.

“In its own right it is an important result because these patients are among the sickest patients, and here we now have a treatment we did not have before.”

The findings are the third treatment to come out of the Recovery trial and come a year on from the ground-breaking discovery that dexamethasone cuts the risk of death by a third. 

Tocilizumab, an anti-inflammatory arthritis drug, was also found to reduce the risk of death by around 14 per cent. 

However, Regeneron’s monoclonal antibody is the first antiviral to be found to be effective. Antivirals target the virus itself and not just the dangerous inflammation it causes, which dexamethasone and tocilizumab soothe. 

‘I’m asking the health service to gear up’

The UK Government established the Antiviral Taskforce earlier this year in the hope that two effective virus-targeting drugs can be approved by the autumn that can be taken at home as a pill. 

Professors Peter Horby and Martin Landry both received knighthoods in the Queen’s birthday honour’s list for their work.

On Tuesday, Sir Simon Stevens, the head of the NHS, urged the health service to "gear up" to provide the drug to patients.

He told the NHS Confederation virtual conference: "We expect that we will begin to see further therapies that will actually treat coronavirus and prevent severe illness and death.

"Today I’m asking the health service to gear up for what are likely to be a new category of such treatments – so-called neutralising monoclonal antibodies – which are potentially going to become available to us within the next several months.”