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Ontak (Seragen Inc): Full Drug Profile

Medically reviewed by Min Clinic Staff | Updated: January 2026

Ontak (Seragen Inc) - General Information

A recombinant DNA-derived cytotoxic protein composed of the amino acid sequences for diphtheria toxin fragments A and B (Met 1-Thr 387)-His followed by the sequences for interleukin-2 (IL-2; Ala 1-Thr 133). It is produced in an E. coli expression system.

 

Pharmacology of Ontak (Seragen Inc)

Ontak (Seragen Inc) (Ontak) directs the cytocidal action of diphtheria toxin to cells which express the IL-2 receptor. The human IL-2 receptor exists in three forms, low (CD25), intermediate (CD122/CD132) and high (CD25/CD122/CD132) affinity. Malignant cells expressing one or more of the subunits of the IL-2 receptor are found in certain leukemias and lymphomas including cutaneous T-cell lymphoma (CTCL). Ontak interacts with the high affinity IL-2 receptor on the cell surface and inhibits cellular protein synthesis, resulting in cell death within hours.

 

Ontak (Seragen Inc) for patients

 

Ontak (Seragen Inc) Interactions

No clinical drug interaction studies have been conducted. However, in a single in vivo rodent study denileukin diftitox had no effect on P450 levels.

 

Ontak (Seragen Inc) Contraindications

ONTAK is contraindicated for use in patients with a known hypersensitivity to denileukin diftitox or any of its components: diphtheria toxin, interleukin-2, or excipients.

 

Additional information about Ontak (Seragen Inc)

Ontak (Seragen Inc) Indication: For treatment of cutaneous T-cell lymphoma Mechanism Of Action: Ontak binds to the high-affinity IL-2 receptor complex. The IL-2 receptor (Tac) subunit is expressed on activated but not resting lymphocytes. The diphtheria toxin associated with Ontak then selectively kills the IL-2 bearing cells. Drug Interactions: Not Available Food Interactions: Not Available Generic Name: Denileukin diftitox Synonyms: DT; Diphtheria toxin precursor; NAD(+--diphthamide ADP- ribosyltransferase) Drug Category: Antineoplastic Agents Drug Type: Biotech; Approved; Investigational Other Brand Names containing Denileukin diftitox: Ontak (Seragen Inc); Absorption: Not Available Toxicity (Overdose): Not Available Protein Binding: Not Available Biotransformation: Not Available Half Life: 70-80 min Dosage Forms of Ontak (Seragen Inc): Solution Intravenous Chemical IUPAC Name: Diptheria toxin-Interleukin-2 fusion protein Chemical Formula: C2560H4042N678O799S17 Denileukin diftitox on Wikipedia: https://en.wikipedia.org/wiki/Denileukin_diftitox Organisms Affected: Humans and other mammals