What Are Monoclonal Antibodies and How Do They Work?

This article was last updated August 2021

As America’s biopharmaceutical companies work around the clock to research and develop vaccines and treatments to help fight COVID-19, scientists have discovered certain medicines that can help reduce the length and severity of a coronavirus infection. Known as “monoclonal antibodies,” a number of these treatments have received emergency use authorizations (EUAs) from the U.S. Food and Drug Administration (FDA) for the treatment of COVID-19.

Monoclonal antibodies have been around for decades and continue to play a central role in advancing our ability to treat against a range of chronic diseases, including cancer and auto-immune conditions. By building on vast stores of knowledge and information about how these treatments interact with the immune system and can be used to counteract disease, America’s biopharmaceutical researchers have been able to rapidly hone in on and develop monoclonal antibodies that are targeted treatments against the coronavirus.

How monoclonal antibodies help fight disease

The immune system relies on antibodies to detect and destroy harmful substances. After discovering a potential invader—such as a virus, bacteria or fungus—the human body produces antibodies that attach to a part of the invader (usually a protein on its surface), which is called an antigen. Once an antibody binds to an antigen, it acts as a signal to other cells in the immune system to attack and destroy it.

While much of the recent focus of these products has been on COVID-19, monoclonal antibodies are also used to fight diseases such as cancer, rheumatoid arthritis and multiple sclerosis. The way they function may be different, depending on the type of disease and the target of the antibody:

• COVID-19: Decades of biopharmaceutical R&D has enabled the development of targeted monoclonal antibody therapies to treat COVID-19. Monoclonal antibodies have the ability to be administered—often if the virus is discovered within the first 10 days—in outpatient settings and may reduce hospitalization and morbidity by lowering a patients viral load. Additionally, monoclonal antibodies can be administered proactively after a potential exposure (post-exposure prophylaxis).

  To date, numerous monoclonal antibodies have been authorized for emergency use that mimic the function of our immune system to help fight COVID-19 by blocking the ability of COVID-19 to attach and enter human cells and/or helping to clear cells which are already infected. The virus must enter the cells to reproduce, as it cannot replicate on its own. By preventing it from doing so or clearing cells in which the virus has already entered, these treatments can help slow the spread of a person’s infection, potentially reducing the length and severity of symptoms.

  In addition to targeted monoclonal antibody therapies, decades of R&D for monoclonal antibodies to treat immune system disorders enabled scientists to repurpose approved monoclonal antibodies to treat complications of COVID. As the number of authorizations continues to increase due to biopharmaceutical R&D, patients benefit by having increased treatment options should they become exposed to or infected with the COVID-19 virus.

• Cancer: Ordinarily, if a cell experiences a genetic mutation that could lead to uncontrolled growth, it is detected and repaired or recognized and quickly destroyed by our immune system. However, sometimes a group of cancerous cells trick the body to avoid detection, allowing them to grow unrestricted. Other times, cancer can weaken a person’s immune system to a point where the body cannot effectively fight the disease on its own. Some monoclonal antibody treatments counteract these changes by reversing a tumor’s ability to avoid detection or strengthening the existing immune system response, which helps the body’s natural defenses to find and fight the disease. 
• Auto-immune conditions: Auto-immune conditions like rheumatoid arthritis or multiple sclerosis result when a person’s immune system mistakenly identifies normal, healthy cells as foreign substances and produces antibodies against them. Monoclonal antibodies can help blunt the body’s attack on itself by blocking the proteins responsible for destroying the healthy tissue.  

For the past few decades, researchers have applied our growing understanding of how the immune system fights disease to the development of new treatments, which has led to innovative medicines like monoclonal antibodies. Now scientists are taking those lessons to battle infectious diseases like COVID-19.

But it doesn’t stop there. The knowledge we’ve gained in the fight against the pandemic will have broad implications for a range of diseases, which may lead to future innovations in those areas as well. Innovation is iterative, and it’s how industry, in collaboration with the NIH, academia, patients and many other stakeholders leads the way to treat and defend in a wide arrange of diseases.