Antibodies are our natural response to infection. They can be taken from the blood of recovered patients or – using modern technology – manufactured synthetically in a laboratory.
The idea of using antibodies as a medical treatment dates back to the 1890s, when Emil von Behring successfully treated children with a severe bacterial infection called diphtheria using serum containing antibodies from the blood of horses recently exposed to the same bacteria. This discovery earned him the first Nobel Prize in medicine.
Almost a century later, scientists Georges JF Köhler and César Milstein learned to design cells that made many copies of a single antibody that could be used to treat disease in the 1970s. These drugs, called monoclonal antibodies , use a high and concentrated number of identical antibodies to attack a very specific target.
The first monoclonal antibody was approved for kidney transplant rejection in the 1980s. As of 2019, the Food and Drug Administration had approved 79 monoclonal antibodies.
“Antibodies form some of the most important drugs in the world for treating everything from cancer to autoimmune diseases,” said Dr. Eline Luning Prak, professor of pathology at the University of Pennsylvania.
Medicines, sometimes called “biologics,” treat a wide variety of illnesses – from cancer to eczema to certain types of arthritis. Humira, the branded version of a drug called adalimumab, was the world’s best-selling drug in 2018, bringing in $ 19.9 billion in revenue for drug maker AbbVie.
And last week, biotech company Regeneron – the same company that makes the drug Trump received – gained FDA approval for the first Ebola treatment, Inmazeb, a mixture 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 yet to be proven effective – block the ability of the virus to attach to and infect body cells. Companies like Regeneron, Eli Lilly and AstraZeneca are currently in late testing.
“These antibodies were designed to bind to very specific sites on the SARS-CoV-2 spike protein,” said Dr. Thomas Campbell, a doctor in the University of Colorado School of Medicine, who heads the Colorado site for Regeneron’s COVID. -19 antibody treatment trials.
“It’s a quick way to protect yourself when you’re already in trouble,” Prak said. The drugs are designed to protect patients who are already infected when the body does not have enough time to make its own immune response.
Monoclonal antibodies are not the same as convalescent plasma – another high-level COVID-19 experimental treatment. However, the treatments are similar, both providing a shortcut to reaching the body’s natural defense against a foreign invader – a concept called passive immunity.
Convalescent plasma is “a mixture of hundreds or thousands of different antibodies” that target multiple sites on the virus, according to Prak. Monoclonal antibody treatments have a high concentration of a single specific antibody, which makes the drug more potent than convalescent plasma.
These treatments, which are used for a wide range of illnesses, are not without risk. Depending on where in the body the antibodies bind, drugs can have different effects. Pharmaceutical company Genentech, for example, withdrew efalizumab, originally approved to treat psoriasis, from the US market because it was associated with a risk of fatal brain infections in 2009.
Another company, Janssen, stopped making a synthetic antibody drug in 2010 in part because of 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 drug can repel the virus. And they say that even if it works, the protection will likely only last a short time.
“If they only last several weeks to a month, 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 novel coronavirus, and give the body longer lasting immunity.
But experts say monoclonal antibodies could be a “bridge” to one vaccine and work in tandem with another to control the pandemic.
“The people most at risk for COVID are those who might organize rather poor vaccine responses,” Prak said. “So it is in this population that this type of therapy could be very useful. ”
Miranda Rosenberg, MD, is a dermatology resident at the University of Miami and a contributor to the ABC News medical unit.