The optimal targeted therapy would be directed against structures that are specific only to cancer cells, but not to the body’s healthy tissues. Given that the tumor originates from and is a part of the body, finding such structures is extremely difficult.
As science progresses, more and more mechanisms that drive tumor growth are being discovered. Thus, new targets for targeted therapy are being identified, and promising new drugs are being developed that block these driving mechanisms.
Drugs from this group are divided into two types: small molecules and monoclonal antibodies. Small molecules can easily enter cells and therefore their targets are intracellular structures. Monoclonal antibodies cannot enter cells freely. They bind to specific targets (receptors) on the cell surface.
In some types of tumors, a specific target is known to be present in all patients and therefore all patients receive the specific targeted therapy. In other cases, only a proportion of tumors are susceptible to targeted therapy. To this end, tumor material archived at surgery or biopsy should be tested to see whether it contains targets for targeted therapy. There are cases where a new biopsy from the tumor or a special blood test is required.