[Principles and method of action of targeted therapies].

Conventional cytotoxic therapy is usually characterized by low specificity and considerable side effects. Targeted therapy, by contrast, allows for a specific inhibition with an acceptable side effect profile. A prerequisite for the development of such a therapy, however, is the identification and characterization of the molecular mechanisms that lead to tumor growth. Antibody-based targeted therapies usually attack cell membrane-bound or extracellular proteins, while tyrosin kinase inhibitors usually act at intracellular domains of transmembranous proteins. Both strategies ultimately lead to an inhibition of the signal transduction cascade and thereby block increased cell proliferation, metastasis, or the production of new blood or lymph vessels.