Scientists in the UK have just recruited the world’s first participants in a new study with long-acting antibodies.
If the treatment is effective, it could offer those who have already been exposed to SARS-CoV-2 protection against the development of COVID-19.
“We know that this combination of antibodies can neutralize the virus,” says virologist Catherine Houlihan, a virologist at University College London Hospitals (UCLH).
So, we hope to find that administering this injection treatment can lead to immediate protection against the development of COVID-19 in people who have been exposed – when it would be too late to provide a vaccine.
It may not be the first COVID-19 antibody treatment you have heard of. US President Donald Trump was given monoclonal antibodies when he came down with the disease, and in the US two different antibody treatments – casirivimab and imdevimab – received emergency approval in November.
But these antibody treatments are given to patients with mild to moderate COVID-19 who are at risk of progressing to a severe version of the disease.
“In a clinical study of co-administered patients with COVID-19, casirivimab and imdevimab showed that they reduced COVID-19-related hospitalization or emergency room visits in patients at increased risk of disease progression within 28 days after treatment compared to placebo, “the FDA explained in a press release when the drugs were approved.
This new antibody therapy, called AZD7442 and developed by UCLH and AstraZeneca, is a little different.
AZD7442 is a combination of two monoclonal antibodies AZD8895 and AZD1061, both of which target the SARS-CoV-2 protein receptor binding domain.
“By targeting this region of the virus’s spike protein, antibodies can block the virus from attaching to human cells and therefore are expected to block the infection,” the team wrote on US ClinicalTrials.gov.
“Amino acid substitutions have been introduced into antibodies to prolong their half-life, which should prolong their potential prophylactic benefit and decrease Fc effector function, to reduce the potential risk of improving antibody-dependent disease.”
Antibodies are small Y-shaped proteins that attach to a specific section – called an antigen – of a virus, bacterium or other pathogen and either “label” it to be attacked by the immune system, or directly block the pathogen to invade our cells.
Normal antibodies are produced by your body after an infection, while monoclonal antibodies are cloned in a laboratory and can be injected into an already infected person to give the immune system a helping hand.
The researchers hope that AZD7442 – which is just beginning the Storm Chaser study (the name of the phase 3 study) – will offer protection to those who have been exposed to the virus but have no symptoms yet. Effectively, they are trying to stop COVID-19 from happening in the first place.
“If you are dealing with outbreaks in environments such as nursing homes or if you have patients at high risk for severe COVID, such as the elderly, then this could save a lot of lives,” University of East England said infectious disease expert Paul Hunter the Guardian.
“If you live with your elderly grandmother and you or someone else in the house gets infected, then you could give her that to protect her.”
But he also hopes it could be effective in the long run, over a period of 6-12 months, which means that people who cannot get the vaccine for medical reasons have another option to stay safe from the disease.
Researchers are looking at how this might 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 and who have conditions such as cancer and HIV that may affect their immune system’s ability to respond to a vaccine,” said Nicky Longley, UCLH’s infectious disease consultant. The Guardian.
“We want to reassure anyone for whom a vaccine may not work that we can offer an equally protective alternative.”
We look forward to seeing where this goes.