Antibodies are attractive to biotech and pharmaceutical companies because they (antibodies) are already an important part of the body's self defense system. Indeed, they are normally produced by the body's immune system in order to fight diseases. The also tend to have a relatively shorter time to market than man other drugs. They are most prominently being used to develop new drugs and treatements for cancer or oncology.
They are part of a class of proteins called immunoglobulins, of which I will go into more detail on later. Antibodies bind to particular target antigens (viruses,parts of cells etc) in a specific way. As each antibody binds to its target antigen, drugs using them , can be highly specified. Furthermore, since they are already part of the bodies system, they tend to be efficacious with less safety concerns (side effects) than many other class of drug.
Developers aim for a high degree of specificity with antibodies because this helps to increase the chances of eliminating the disease. Unfortunately, for things like cancer, the body does not ordinarily make antibodies to fight the cancerous cells. This is because cancer is an abnormal growth of the existing body cells, not a foreign antigen.
Antibody Therapies for Cancer
Therefore, in oncology (cancer) the developers need to create special antibodies which guide and then bind to a target antigen. Now, remember I said I would go back to immunoglobulins?
Simply put, antibodies are part of a class of proteins called immunoglobulins. They are naturally occurring proteins are produced by the immune system in response to antigens.
They are "Y" shaped in form-usually- Immunoglobulins consist of two heavy chains and two light chains. The heavy and light chains are composed of two distinct domains: the variable region and the constant region. The variable region-which is the antigen binding site- is located at the tip of the arms of the "Y", and is called Fab. The rearrangement of the genes in the Fab domain gives antibodies their diversity and ability to be adjusted to target particular antigens.
These changes amount to a wide range of antigen specificities. The constant region is called the fragment crystallisable region and, represents the tail if the "Y". This region can bind to proteins and cause destruction of target cells by attacking their membranes.
The fragment crystallisable (FC) region can also bind to receptors on the surfaces of immune effector cells, which can then activate the functions that kill cells of the targeted antibody cell. Antibodies can also be developed to block growth signals in tumors.
In fact, this science is so successful that monoclonal antibody therapies are predicted to be five of the top ten selling blockbuster drugs within the next few years.
Reuters Article http://www.reuters.com/article/idUSLDE63C0BC20100413 (accessed 20 Nov)