Metaphorically, antibodies can be described as unarmed guided missiles, which have extraordinary precision and targeting abilities, but once they hit the target, they inflict minimal damage. Chemotherapy and radiotherapy can be described as artillery, very powerful, but unguided. In order to optimally use the two, the most logical step is arming those unarmed missiles with a variety of explosives. Using the same reasoning, there is a true need to develop anti-cancer therapies which have an antibody-like specificity as well as chemo/radio-therapy-like potency. Doing so enables us to take advantage of the selectivity of antibodies and the potent toxic activity of chemo/radio-therapy, thus creating superior cancer treatments. The antibody binds the target on the tumor, delivers its payload and kills the cell. Arming antibodies with effector molecules like chemotherapy agents and radio-isotopes results in a hybrid agent referred to as an Immunoconjugate. An antibody which is not conjugated to an effector is referred to as “naked” antibody.
Antibodies are naturally occurring proteins that help our body fight bacteria, viruses and cancer. Upon its release into the blood stream, an antibody can identify and bind a specific pathogen, and by doing so, it can neutralize the pathogen or “flag” it for attack by the immune system. Our body is able to generate antibodies against a virtually infinite number of targets, thanks to brilliant biological mechanisms developed throughout the course of evolution. Once a pathogen enters our body, our immune system conducts a high-throughput screen of all the antibodies it can generate (around 10 billion different antibodies). After the appropriate antibodies are selected, special white blood cells called B-cell lymphocytes enter a mass production phase in which large amounts of the selected antibodies are secreted into the blood stream “in search” of their specific target. The combination of diversity on the one hand and specificity on the other hand, makes antibodies a crucial component of our defense mechanism. This combination also makes antibodies an extremely popular platform among drug companies.