Scientists in the UK have just recruited the world’s first participants to participate in a new long-term antibody study.
If the treatment is effective, it can protect those already exposed to SARS-CoV-2 from developing COVID-19.
“We know that this combination of antibodies can neutralize the virus,” explains virologist Catherine Houlihan of University College London Hospitals (UCLH).
“So we hope to find that giving this treatment by injection can lead to immediate protection against the development of COVID-19 in exposed humans – when it would be too late to offer a vaccine.”
This may not be the first antibody treatment for COVID-19 that you have heard of. Outgoing US President Donald Trump was given monoclonal antibodies when he contracted the disease, and in the US, two different antibody treatments – casirivimab and imdevimab – received emergency clearances in November.
But those antibody treatments are given to patients with mild or moderate COVID-19, who are at risk of progressing to a severe version of the disease.
In a clinical study in patients with COVID-19, casirivimab and imdevimab, administered together, were shown to reduce COVID-19-related hospitalization or emergency room visits in patients at high risk of disease progression within 28 days of treatment compared to placebo., ”the FDA stated in a press statement when the drugs were approved.
This new antibody therapy, called AZD7442 and developed by UCLH and AstraZeneca, is a bit different.
AZD7442 is a combination of two monoclonal antibodies AZD8895 and AZD1061, both of which target the receptor binding domain of the SARS-CoV-2 spike protein.
“By targeting this area of the virus ‘spike protein, antibodies can block the virus’ attachment to human cells and are therefore expected to block infections,” the team wrote on the US ClinicalTrials.gov website.
“Amino acid substitutions have been introduced into the antibodies to both extend their half-lives, which should extend their potential prophylactic benefit, and reduce Fc effector function to reduce the potential risk of antibody-dependent enhancement of the disease.”
Antibodies are small Y-shaped proteins that cling to a particular section – called an antigen – of a virus, bacteria, or other pathogen, and ‘tag’ it to be attacked by the immune system, or block the pathogen directly around our cells.
Normal antibodies are produced by your body after an infection, while monoclonal antibodies are cloned in a lab and can be injected into an already infected person to lend the immune system a helping hand in the fight.
The researchers hope that AZD7442 – which is just starting the Storm Chaser trial (the name for the phase 3 trial) – will provide protection for those who have been exposed to the virus but have no symptoms yet. In fact, they are trying to stop COVID-19 at all.
“If you are dealing with outbreaks in settings such as nursing homes, or if you have patients who are particularly at risk for severe COVID, such as the elderly, it can save a lot of lives,” said University of East Anglia infectious disease expert Paul Hunter The Guardian.
“If you live with your elderly grandmother and you or someone else in the house becomes infected, you can give this to her to protect her.”
But they also hope it can be effective in the longer term, over a 6-12 month period, meaning people who can’t get the vaccine for medical reasons will have another option for protecting themselves from the disease.
The researchers are looking at how this could work for people with compromised immune systems in a second study called PROVENT.
“We will recruit people who are older or in long-term care with conditions such as cancer and HIV that can affect the ability of their immune systems to respond to a vaccine,” said Nicky Longley, infectious diseases adviser at UCLH. The Guardian.
“We want to reassure anyone for whom a vaccine may not work that we can offer an alternative that is just as protective.”
We look forward to seeing where this leads.