UK scientists have just recruited the world’s first participants to take part in a new study of long-acting antibodies.
If the treatment is effective, it can give 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,” explains virologist Catherine Houlihan of University College London Hospitals (UCLH).
“So we hope to find that administering this treatment by injection can lead to immediate protection against the development of COVID-19 in people who have been exposed – when it would be too late to offer a vaccine.”
This may not be the first antibody treatment for COVID-19 you’ve ever heard of. Outgoing U.S. President Donald Trump received monoclonal antibodies when he contracted the disease and, in the U.S., two different antibody treatments – casirivimab and imdevimab – received emergency approval in November.
But these 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 trial of patients with COVID-19, casirivimab and imdevimab, administered together, have been shown to reduce COVID-19-related hospitalization or emergency room visits in patients at high risk of disease progression within 28 days after treatment , when compared to placebo, “explained the FDA 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, which target the SARS-CoV-2 spike protein receptor binding domain.
“By targeting this region of the virus’s spike protein, antibodies can block the virus from binding to human cells and therefore are expected to block infection,” the team wrote on the US ClinicalTrials.gov website.
“Amino acid substitutions have been introduced in the antibodies to extend their half-lives, which should extend their potential prophylactic benefit, and decrease the effector function of Fc, in order to decrease the potential risk of increasing antibody-dependent disease.”
Antibodies are small Y-shaped proteins that attach to a specific section – called an antigen – of a virus, bacteria or other pathogen, and “tag” to be attacked by the immune system or directly block the pathogen from invading our cells.
Normal antibodies are produced by the body after an infection, while monoclonal antibodies are cloned in a laboratory and can be injected into an already infected person, to help the immune system fight.
The researchers hope that AZD7442 – which is just beginning the Storm Chaser study (the name of its phase 3 trial) – will provide protection for those who have been exposed to the virus but still have no symptoms. In effect, they are trying to prevent COVID-19 from happening in the first place.
“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, this can save many lives,” University of East Anglia Infectious Disease Specialist Paul Hunter said The Guardian.
“If you live with your elderly grandmother and you or someone else in the house gets infected, then you can give it to her to protect her.”
But they also expect it to be effective over the long term, for a period of 6-12 months, meaning that people who cannot receive the vaccine for medical reasons have another option to protect themselves from the disease.
The researchers are looking at how this could work for people with compromised immune systems in a second trial called PROVENT.
“We will be recruiting people who are older or on long-term treatment and who have diseases such as cancer and HIV that can affect their immune system’s ability to respond to a vaccine,” said UCLH infectious disease consultant Nicky Longley. The Guardian.
“We want to reassure anyone for whom a vaccine may not work that we can offer such a protective alternative.”
We are looking forward to seeing where this will take us.