Optimizing denileukin diftitox (Ontak®) therapy

Denileukin diftitox (Ontak (R)) is a novel recombinant fusion protein consisting of peptide sequences for the enzymatically active and membrane translocation domain of diphtheria toxin linked to human IL-2. Denileukin diffitox specifically binds to IL-2 receptors on the cell membrane, is internalized via receptor-mediated endocytosis and inhibits protein synthesis by ADP ribosylation of elongation factor 2, resulting in cell death. This article focuses on the clinical trial that led to the US FDA approval of the drug for cutaneous T-cell lymphoma in 1999, and other investigational studies for hematologic malignancies, recurrent and refractory chronic lymphocytic leukemia, non-Hodgkin B-cell lymphoma, graft-versus-host disease and autoimmune disease, demonstrating the activity and adverse effects of the drug.