What is the COVID treatment REGN-COV2?

The news of US President Donald Trump testing positive for coronavirus – and his subsequent treatment regimen – has sparked a flurry of media activity in recent days.
 
According to White House physicians, the leader of the world’s largest economy has been placed on a regimen that contains standard treatments for moderate, severe or critical COVID – including remdesivir and dexamethasone – but also treatments that are yet to pass random clinical trials.
 
To date, the only REGN-COV2 data released by Regeneron Pharmaceuticals, the company developing the new coronavirus treatment given to President Trump, were contained in an investor memo released just over a week ago.
 
But if preliminary results from the seamless phase 1/2/3 trial are proved accurate, the new treatment could help reduce viral load and the time it takes for symptoms to subside, particularly in non-hospitalised patients with COVID-19.
 
‘The greatest treatment benefit was in patients who had not mounted their own effective immune response, suggesting that REGN-COV2 could provide a therapeutic substitute for the naturally-occurring immune response,’ Regeneron President and Chief Scientific Officer George Yancopoulos said.
 
‘These patients were less likely to clear the virus on their own, and were at greater risk for prolonged symptoms. 
 
‘We are highly encouraged by the robust and consistent nature of these initial data, as well as the emerging well-tolerated safety profile, and we have begun discussing our findings with regulatory authorities while continuing our ongoing trials.’
 
The treatment itself, one of five being investigated as part of the UK’s RECOVERY (Randomised Evaluation of COVid-19 thERapY) trial, is a combination of two monoclonal antibodies (REGN10933 and REGN10987) designed specifically to block infectivity of SARS-CoV-2.
 
Professor Dale Godfrey, Immunology Theme Leader at the Doherty Institute, told newsGP Regeneron is one of a number of companies trialling this type of approach, which involves cultivating ‘a cocktail’ of monoclonal antibodies in the lab that can later be injected into coronavirus patients.
  
‘They’ve taken antibody-producing B-cells from individuals who have already been infected, cloned the antibody sequences from individual B cells, and then grown them up to enormous levels, to the point where you have large amounts of these antibodies in a purified form in the lab,’ he said.
 
‘Typically, humans have many different B cells that make many different antibodies against an infection – this is called a polyclonal response. But these scientists take one that works well and make a clone of that – so it’s called a monoclonal antibody.
 
‘Why it’s called a cocktail is because they’ve taken two different monoclonal antibodies and mixed them, grown them up to enormous levels, and injected back into patients. Two different monoclonal antibodies in a cocktail increases the chance of completely blocking the virus and avoiding escape by mutant forms of the virus.
 
‘The idea here is that if you can get antibodies from humans who’ve been infected, select those that block the virus most efficiently, and make a copy of these in the lab, then you can treat infected people with these giving them a big head start. This can help because it takes days to weeks for people to make their own antibodies and this can sometimes come too late.’
 
Professor Godfrey said the treatment works by blocking the spikes that form the coronavirus’ ‘crown’, which the virus uses to attach itself to human cells.
 
‘At the tip of the spike is what we call the receptor binding domain. That’s the part of the spike that binds to our cells, it’s a bit like the hand at the end of the arm,’ he said.
 
‘We know that most people who are infected make antibodies against all parts of the virus. But the parts that are the most important for blocking the virus are those that bind to this receptor binding domain.
 
‘These antibodies have been raised so that can very specifically bind to that “hand at the end of the arm” and block it from binding to our own cells preventing it from gaining access to our cells.’
 
The new treatment, which is derived from previous research into other highly infectious viruses such as Ebola, is so experimental that Australia’s National COVID-19 Clinical Evidence Taskforce (the taskforce) has not yet been able to study its merits.
 
‘The taskforce looks at all published research on all COVID-19 treatments every night,’ taskforce Chair Associate Professor Julian Elliott told newsGP. ‘But this is still in the early stages of development and so there have not yet been any published randomised trials of this.
 
‘[President Trump’s] use is what would be called compassionate access. This does occur when people or a physician may request to use a drug that’s still in development. So that’s not unheard of.’
 
However, Associate Professor Elliott did point out REGN-COV2 is not the only treatment being given to Trump that is experimental in nature.
 
‘Based on reports, it sounds like he’s also taking other medications for which there is no strong evidence,’ he said.
 
‘Zinc and vitamin D have been discussed a lot, but there’s no high-quality evidence supporting their use outside of clinical trials, and we only recommend the use of those agents in the context of clinical trials.’
 
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