Targeted toxins.

Targeted toxins, consisting of tumor-selective ligands coupled to polypeptide toxins, represent a new class of cancer therapeutics that kills malignant cells by inactivating cytosolic protein synthesis and inducing apoptosis. A number of these molecules have been produced under good manufacturing practice conditions and given systemically to patients with a variety of neoplasms. The promising results to date and the remaining pharmacological hurdles are discussed.