Antibodies are our natural response to an infection. They can be harvested from the blood of recovered patients or – using modern technology – synthetically produced in a laboratory.
The idea of using antibodies as medical treatment dates back as early as the 1
Nearly a century later, researchers Georges JF Köhler and César Milstein learned to construct cells that produced many copies of a single antibody that could be used to treat disease in the 1970s. These drugs, known as monoclonal antibodies, use a concentrated, large number of identical antibodies to attack a very specific target.
The first monoclonal antibody was approved for rejection of kidney transplantation in the 1980s. By 2019, the Food and Drug Administration had approved 79 monoclonal antibody drugs.
“Antibodies are some of the most important drugs in the world for treating everything from cancer to autoimmune disease,” said Dr. Eline Luning Prak, Professor of Pathology at the University of Pennsylvania.
The drugs, sometimes referred to as “biological substances”, treat a variety of diseases – from cancer to eczema to certain types of arthritis. Humira, the trademarked version of a drug called adalimumab, was the world’s best-selling drug in 2018, bringing in $ 19.9 billion in sales revenue to drug manufacturer AbbVie.
And this past week, the biotechnology company Regeneron – the same company that makes the drug that Trump received – won FDA approval for the first Ebola treatment, Inmazeb, a blend of three monoclonal antibodies. These antibodies target parts of the external protein that Ebola uses to bind to and infect human cells.
When it comes to COVID-19, antibody drugs – all of which are still experimental and have not yet been shown to work – block the virus’ ability to bind to the body’s cells and infect them. Companies like Regeneron, Eli Lilly and AstraZeneca are currently in late phase trials.
“These antibodies are designed to bind to very specific sites on SARS-CoV-2’s tip protein,” explained Dr. Thomas Campbell, a physician at the University of Colorado School of Medicine who leads the Colorado site of Regeneron’s COVID -19 antibody treatment trials.
“It’s a way to give you quick protection when you’re already in trouble,” Prak said. The drugs are designed to protect patients who are already infected when there is not enough time for the body to make its own immune response.
Monoclonal antibody drugs are not the same as convalescent plasma – another high-profile experimental COVID-19 treatment. However, the treatments are similar, with both providing a shortcut to achieving the body’s natural defenses against a foreign intruder – a concept called passive immunity.
Convalescent plasma is “a mixture of hundreds or thousands of different antibodies” targeted at multiple sites on the virus, according to Prak. Monoclonal antibody treatments have a high concentration of a single, specific antibody, making the drug more potent than restoring plasma.
These treatments used for a wide range of diseases are not without risk. Depending on where in the body the antibodies bind, the substances can give different effects. For example, pharmaceutical company Genentech removed efalizumab, originally approved for the treatment of psoriasis, from the US market because it was associated with a risk of fatal brain infections in 2009.
Another company, Janssen, stopped manufacturing a synthetic antibody drug in 2010, in part due to serious side effects – some of which were potentially fatal.
Although synthetic antibodies are currently being tested as a way to prevent COVID-19, in addition to treating the disease, researchers do not yet know if this type of medication can ward off the virus. And they say that even if it works, the protection will probably only last a short time.
“If they only last several weeks to a month, then they probably won’t be protective in six months or a year,” Campbell explained.
Alternatively, vaccines teach the body to recognize foreign invaders, such as the new coronavirus, and give the body longer-lasting immunity.
But experts say monoclonal antibodies can be a “bridge” to a vaccine and work with one to control the pandemic.
“The people who are most exposed to COVID are the ones who might be fitting pretty bad vaccine responses,” Prak said. “So it’s in the population where this kind of therapy can be very helpful.”
Miranda Rosenberg, MD, is a dermatologist at the University of Miami and a contributor to the ABC News Medical Unit.