TheraRadar

Pharma Intelligence, Simplified

Data updated: Mar 10, 2026

ONTAK

DENILEUKIN DIFTITOX
Oncology Approved 1999-02-05

LYMPHIR (denileukin diftitox-cxdl) is an IL2-receptor-directed cytotoxin indicated for the treatment of cutaneous T-cell lymphoma (CTCL). It is specifically approved for adult patients with relapsed or refractory Stage I-III disease. This therapeutic option is intended for use after a patient has undergone at least one prior systemic therapy.

Source: FDA Label • EISAI INC • CD25-directed Cytotoxin

How ONTAK Works

Denileukin diftitox-cxdl is a fusion protein designed to deliver the cytocidal action of diphtheria toxin to cells expressing the IL-2 receptor. Upon cellular uptake, the diphtheria toxin fragment is cleaved and released, where it inhibits protein synthesis and leads to cell death. This mechanism allows the drug to deplete immunosuppressive regulatory T lymphocytes and exert direct antitumor activity on IL-2R-expressing tumors.

Source: FDA Label
2
Indications
--
Phase 3 Trials
2
Priority Reviews
27
Years on Market

Details

Status
Prescription
First Approved
1999-02-05
Routes
N/A
Dosage Forms
VIAL

Companies

Active Ingredient: DENILEUKIN DIFTITOX

ONTAK Approval History

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What ONTAK Treats

1 indications

ONTAK is approved for 1 conditions since its original approval in 1999. These indications span multiple therapeutic areas including oncology, immunology, and more.

  • Cutaneous T-Cell Lymphoma
Source: FDA Label

ONTAK Boxed Warning

CAPILLARY LEAK SYNDROME Capillary leak syndrome (CLS), including life-threatening or fatal reactions, can occur in patients receiving LYMPHIR. Monitor patients for signs and symptoms of CLS during treatment. Withhold LYMPHIR until CLS resolves, or permanently discontinue based on severity [see Dosage and Administration ( 2.1 , 2.4 ) and Warnings and Precautions ( 5.1 )] . WARNING: CAPILLARY LEAK SYNDROME See full prescribing information for complete boxed warning. Capillary leak syndrome (CLS), ...

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Key Completed Trials

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Completed studies with published results, ranked by significance

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Trial Timeline

Full development history with FDA approval milestones

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Understanding FDA Approval Types
Count Type What it means
- ORIG Original approval - drug first enters market
- SUPPL - Efficacy New indication (new disease/condition approved)
- SUPPL - Labeling Label text changes (warnings, dosing updates)
- SUPPL - Manufacturing Production changes (new facility)
- SUPPL - Chemistry Formulation changes (new dosage strength)

Green lines in the timeline show ORIG and Efficacy approvals - the clinically meaningful milestones.

ONTAK FDA Label Details

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Indications & Usage

FDA Label (PDF)

LYMPHIR is indicated for the treatment of adult patients with relapsed or refractory Stage I-III cutaneous T-cell lymphoma (CTCL) after at least one prior systemic therapy. LYMPHIR is an IL2-receptor-directed cytotoxin indicated for the treatment of adult patients with relapsed or refractory Stage I-III cutaneous T-cell lymphoma (CTCL) after at least one prior systemic therapy.

⚠️ BOXED WARNING

WARNING: CAPILLARY LEAK SYNDROME Capillary leak syndrome (CLS), including life-threatening or fatal reactions, can occur in patients receiving LYMPHIR. Monitor patients for signs and symptoms of CLS during treatment. Withhold LYMPHIR until CLS resolves, or permanently discontinue based on severity [...

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Data Sources

Data sourced from official FDA and NIH databases. Click links to verify on original sources.