Abstract

The selective delivery of drugs to their site of action should increase their therapeutic effectiveness, while minimizing unwanted side effects. In the early 1900s, Paul Ehrlich proposed the potential use of antibodies as carriers of biological agents to the target sites, thus inventing the “magic bullet” concept. With the development of hybridoma technology, it is now possible to produce virtually unlimited quantities of homogenous antibodies having a defined specificity, that is, monoclonal antibodies (MoAbs) that have the potential to fulfill Ehrlich’s vision. MoAbs continue to hold particular promise for cancer-specific drug targeting, with increase in life expectancy in certain solid and hematopoietic tumors such as leukemias, lymphomas, and breast and lung cancers. While a number of therapeutic MoAbs have entered the marketplace, their conjugates are only beginning to realize the promise that was predicted with the advent of the core technology. Currently, antibodies and antibody conjugates represent one of the largest classes of new drug entities under development for the treatment of malignancies and infectious, inflammatory and autoimmune diseases.