Therapeutic potential of anticancer immunotoxins.

Immunotoxins are chimeric proteins consisting of a tumor-specific ligand (antibody, growth factor or peptide) linked to a modified toxin. These molecules bind to cell surface receptors and are subsequently internalized by endocytosis, resulting in cell death. Advances in protein engineering and phage display have enabled the selection of high-affinity targeting moieties. Denileukin diftitox is the only FDA-approved immunotoxin, although others such as BL22 are currently in different phases of development. This review elaborates the key findings of the important clinical studies relating to various chimeric toxins.