TheraRadar
Data updated: May 26, 2026

ONTAK (denileukin diftitox)

Genetic Support Trial Activity: Declining
Oncology Approved 1999-02-05

ONTAK is indicated for the treatment of Cutaneous T-Cell Lymphoma.

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.

Development Insights

Fred Hutchinson Cancer Center conducting 1 trials (14%)
9 indications explored (Moderate)
stage iv melanoma (2 trials)
recurrent melanoma (1 trials)
stage iii melanoma (1 trials)
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

2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
Original
New Indication
New Form
Label Update
6 FDA actions from 1999 to 2020 · 1 indication expansions
Feb 2020 SUPPL
Label · Labeling
Feb 2019 SUPPL
Label · Labeling
Aug 2011 SUPPL
Update · Supplement

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), ...

ONTAK Target & Pathway

Pro

Target

IL-2 (Interleukin 2) Cytokine

ONTAK Competitive Set

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Filters applied: drops same-active-ingredient (505(b)(2) reformulations), route-mismatch (topical vs systemic), and cross-therapeutic-area matches in same-indication rings.

What's emerging in ONTAK's indications

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Phase 3 candidates targeting molecules with no FDA-approved drug, in indications ONTAK treats. First-in-class if their pivotal trials read out positive.

Drugs Similar to ONTAK

3 of 9

FDA-approved drugs for similar conditions. Compare mechanisms and indications to understand treatment alternatives.

BEXAROTENE
BEXAROTENE
1 shared
BIONPHARMA
Shared indications:
Cutaneous T-Cell Lymphoma
ISTODAX
ROMIDEPSIN
1 shared
Bristol-Myers Squibb
Shared indications:
Cutaneous T-Cell Lymphoma
LYMPHIR
DENILEUKIN DIFTITOX-CXDL
1 shared
CITIUS PHARMS
Shared indications:
Cutaneous T-Cell Lymphoma
📋

Clinical Trial Registry

7 trials
Trial Sponsor ID Phase Status Title
NCT00945269 2271.00 NCI-2010-00738, K12CA076930 Ph 1, Ph 2 terminated Therapeutic Autologous Lymphocytes, Aldesleukin, and Denileukin Diftitox in Treating Patients With Stage III-IV Melanoma
NCT01127451 results posted E7272-701 Ph 2 completed Study of Denileukin Diftitox in Participants With Stage IIIC and Stage IV Melanoma
NCT00632827 results posted 072518 NCI-2011-01285 Ph 2 terminated Treatment of PTCL With Aggressive Induction Therapy Followed by Autologous SCT Using Denileukin Diftitox (Ontak)
NCT01106950 results posted 2010LS010 MT2010-02, 1003M79954 Ph 2 terminated Haploidentical Natural Killer Cells to Treat Refractory or Relapsed Acute Myelogenous Leukemia (AML)
NCT00460109 results posted NCCTG-N0682 NCI-2009-00662, CDR0000539551 Ph 2 completed Rituximab and Denileukin Diftitox in Treating Patients With Previously Untreated Stage III or Stage IV Follicular B-Cell Non-Hodgkin's Lymphoma
NCT00726037 results posted 200732 Ph 2 terminated A Pilot Study, Evaluating the Efficacy of Regulatory T-cell Suppression by Ontak in Metastatic Pancreatic Cancer
NCT00801918 AAAC8963 Ph 2 withdrawn Denileukine Diftitox for Relapsed ALCL
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Active Pipeline

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Ongoing clinical trials by development phase

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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

Indications & Usage

FDA Label (PDF)

ONTAK is indicated for the treatment of Cutaneous T-Cell Lymphoma.

⚠️ 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.

How We Calculate These Metrics

Trial Activity Stage

Measures the current development activity pattern based on trial phases, status, and trends. Important: This measures R&D activity, not commercial lifecycle.

Trial statuses: "Active" means recruiting or ongoing. "Completed" means reached planned endpoint. "Terminated" means stopped early—often due to safety, efficacy, or business reasons.

  • Growth: High proportion of early-phase trials (Phase 1/2), active development
  • Expansion: Significant Phase 3 activity, approaching or pursuing approvals
  • Mature: Substantial Phase 4 post-marketing studies
  • Stable: Mixed phase distribution, steady development
  • Declining: Low active trial ratio, reduced R&D investment