Denileukin diftitox, sold under the brand name Ontak among others, is an anti-cancer medication used for the treatment of adults with T-cell lymphoma. It is an IL2-receptor-directed cytotoxin. It is an engineered protein combining interleukin-2 and diphtheria toxin.

Medical uses

Denileukin diftitox is indicated for the treatment of adults with relapsed or refractory stage I-III cutaneous T-cell lymphoma after at least one prior systemic therapy.

Adverse effects

The prescription label contains a boxed warning that capillary leak syndrome (CLS), including life-threatening or fatal reactions, can occur in people receiving denileukin diftitox.

Society and culture

Legal status

In 1999, denileukin diftitox was approved by the US Food and Drug Administration (FDA) for the treatment of cutaneous T-cell lymphoma.