Toxin-Based Therapeutic Approaches

Shapira, Assaf; Benhar, Itai

The term "immunotoxin" classically refers to molecules which consist of a protein toxin linked to a targeting moiety derived from the immune system (such as an antibody or an antibody fragment); but frequently expanded to include other target-specifying ligands (such as a cytokine). The idea of development of a "magic bullet" that has a specific attraction to a disease-causing target, avoiding healthy body cells, was originally suggested by Paul Ehrlich over 100 years ago [5] [6] [7] . However, it was only in the 1970s that therapeutic agents composed of toxins conjugated to antibodies against cell surface antigens were shown to kill tumor cells [8, 9] . Since then, many hybrid molecules consisting of a toxin coupled with a specific targeting antibody/ligand were developed; most of them are targeted against tumor cells [10] (Figure 1 ).