Denileukin Diftitox · Lymphir, Ontak

What is Denileukin Diftitox?

Denileukin diftitox is a fusion protein combining human interleukin-2 with diphtheria toxin fragments. It binds IL-2 receptors on target cells, and after internalization, the toxin catalyzes ADP-ribosylation of elongation factor 2, inhibiting protein synthesis and causing cell death.

Summary written with AI from the sources listed at the end of this page.

At a glance

Also known as

Lymphir, Ontak, E7777, DAB389 IL2, ONTAK

Drug type

Fusion protein

Targets

IL-2 receptor (IL2RA), elongation factor 2 (EEF2) (secondary target)

Mechanism

Kills target cells, directed at IL-2 receptor (IL2RA)

Pathways

protein synthesis inhibition, translation inhibition

Therapy area

Oncology

Developer

Eisai Inc

In trials of

RDY

FDA status

Approved as Lymphir, Ontak (February 5, 1999), BLA103767 · FDA label

UNII

25E79B5CTM

✅ FDA-approved uses

• Relapsed or refractory Stage I-III cutaneous T-cell lymphoma (Lymphir)

From the indications section of the FDA label (version of Jan 23, 2025). Read the full label for the exact wording, limitations and safety information.

🧪 Clinical trials

Trials of the companies BioRadar tracks, from ClinicalTrials.gov, most advanced phase first.

Conditions studied

Epithelial Ovarian Cancer

Other drugs acting on IL2RA

Sources

• FDA Purple Book
• FDA label (DailyMed)
• FDA label Lymphir (2025-01-23), indications
• NCI Thesaurus
• ClinicalTrials.gov NCT05200559

Updated Oct 3, 2026.