Antibody Drugs Might Be A Powerful Weapon Fighting COVID-19

  • Antibody drugs are an important part in the field of biotechnology-based pharmaceuticals. The use of antibodies to diagnose and treat diseases has long been a goal pursued by pharmaceutical scientists. Antibody binding to target antigens has advantages of high specificity, efficacy, and safety, and has been clinically used for various malignancies and autoimmune diseases, and antibody drugs have become one of the fastest-growing drug subclasses worldwide in the last five years.

    As antibody discovery technologies and methods growing mature, antibody drug development is becoming increasingly diverse, and other forms of antibodies including antibody-drug conjugates (ADCs), bispecific antibodies (bsAb), and nanobodies are on the rise. The global pandemic of COVID-19 has also focused scientists' attention on antibody drug development.

    Monoclonal antibodies have become one of the hot spots for drug development for COVID-19 prevention and treatment due to their high specificity, high activity and relatively clear therapeutic mechanism. With the maturation and application of single B-cell antibody screening technology, more and more potential neutralizing antibodies have been discovered.

    Neutralizing antibodies are a class of antibodies produced by human B lymphocytes that bind to antigens on the surface of pathogenic microorganisms such as viruses and bacteria when they invade human cells, thus preventing the specific molecules expressed by the pathogenic microorganisms from binding to cell surface receptors. In many cases, the body's own production of high-affinity neutralizing antibodies is very limited, and it takes a long time to produce effective neutralizing antibodies. If the pathogenic microorganism has a very high affinity for binding to cell surface receptors, or if the amount of neutralizing antibodies produced by the body after infection is insufficient, neutralizing antibody drugs can be used as "outside help".

    Unlike other antiviral drugs, neutralizing antibody drugs not only have a therapeutic effect, but also have a preventive effect by protecting the body from viral infections. This is because after the administration of antibody drugs, if the virus infects the body, the "outside helper" will bind with the antigen on the surface of the virus and prevent it from binding to the receptor on the cell surface.

    Studies have revealed that the invasive "bridge" of the SARS-CoV-2 is its spike protein, which binds to the cell surface receptor, angiotensin-converting enzyme 2 (ACE2), enabling the virus to invade the host cell. The receptor binding domain of the spike protein is an important receptor binding site on the surface of the coronavirus, so it is an important target for the development of antiviral neutralizing antibodies. By blocking this kind of binding, the antibody drug can block the contact between the virus and human cells.

    So, can antibody drugs replace vaccines? The answer is no. Although they both provide protection, vaccines and monoclonal antibodies have different mechanisms of action.

    In simple terms, vaccines are antigens that act to stimulate the body to produce immunity for preventive purposes, which is a form of active immunity, while antibody drug is a direct input of antibodies, a form of passive immunity that allows the body to gain immunity immediately, but it usually works for a short period of time, and is generally used for treatment or for emergency prevention in special cases.