Therapeutic antibodies

Therapeutic antibodies are a class of medicines designed to target specific molecules within the body, with the aim of treating or managing diseases. These antibodies are engineered to mimic the immune system's ability to fight off harmful pathogens, such as bacteria and viruses, but are specifically directed against molecules that are associated with diseases, including various types of cancer, autoimmune disorders, and infectious diseases.

History

The development of therapeutic antibodies marks a significant milestone in the field of biotechnology and pharmacology. The first monoclonal antibody for therapeutic use, Muromonab-CD3 (Orthoclone OKT3), was approved by the U.S. Food and Drug Administration (FDA) in 1986 for the prevention of kidney transplant rejection. Since then, advancements in molecular biology and genetic engineering have led to the creation of a wide variety of therapeutic antibodies, each designed for specific targets and purposes.

Types of Therapeutic Antibodies

Therapeutic antibodies can be classified into several types based on their source and method of production:

• Murine antibodies are derived entirely from mice and were among the first types of therapeutic antibodies developed. However, their use is limited due to the human immune system recognizing the antibodies as foreign, leading to potential allergic reactions.
• Chimeric antibodies are composed of murine variable regions fused with human constant regions, reducing immunogenicity and improving their therapeutic potential.
• Humanized antibodies have even more of the mouse components replaced with human parts, except for the antigen-binding sites, further reducing the risk of immune reactions.
• Fully human antibodies are produced using transgenic mice or phage display libraries and do not contain any mouse protein, minimizing the risk of immune response.

Mechanism of Action

Therapeutic antibodies work by binding to specific targets, known as antigens, on the surface of cells or circulating in the body. This binding can directly neutralize the target molecule's activity or mark the cell for destruction by the immune system, a process known as antibody-dependent cellular cytotoxicity (ADCC). Additionally, some therapeutic antibodies can block the interaction between two molecules, preventing a biological response that contributes to disease progression.

Applications

Therapeutic antibodies have been developed for a wide range of applications, including:

• Oncology: Many therapeutic antibodies target antigens expressed on cancer cells, helping to directly kill the tumor cells or inhibit their growth. Examples include trastuzumab (Herceptin) for HER2-positive breast cancer and rituximab (Rituxan) for non-Hodgkin lymphoma.
• Autoimmune diseases: Antibodies such as adalimumab (Humira) and infliximab (Remicade) target tumor necrosis factor-alpha (TNFα), a cytokine involved in inflammation, to treat conditions like rheumatoid arthritis and Crohn's disease.
• Infectious diseases: Palivizumab (Synagis) is a monoclonal antibody used to prevent severe respiratory syncytial virus (RSV) infections in high-risk infants.

Challenges and Future Directions

Despite their success, the development and use of therapeutic antibodies face several challenges, including high production costs, the need for intravenous administration, and the potential for adverse immune reactions. Ongoing research is focused on improving the efficacy, safety, and delivery methods of therapeutic antibodies, as well as expanding their applications to new diseases.

See Also

• Monoclonal antibodies
• Biopharmaceutical
• Immunotherapy
• Pharmacology