You may experience a serious or life-threatening reaction while you receive a dose of denileukin diftitox injection. You will receive each dose of medication in a medical facility, and your doctor will monitor you carefully while you are receiving the medication. Your doctor will prescribe certain medications to prevent these reactions. You will take these medications by mouth shortly before you receive each dose of denileukin diftitox. If you experience any of the following symptoms during or for 24 hours after your infusion, tell your doctor immediately: fever, chills, hives, difficulty breathing or swallowing, slowed breathing, fast heartbeat, tightening of the throat, or chest pain.

Some people who received denileukin diftitox developed life-threatening capillary leak syndrome (a condition that causes the body to keep excess fluid, low blood pressure, and low levels of a protein [albumin] in the blood). Capillary leak syndrome may occur up to 2 weeks after denileukin diftitox is given and may continue or get worse even after treatment is stopped. If you experience any of the following symptoms, call your doctor immediately: swelling of the hands, feet, ankles, or lower legs; weight gain; shortness of breath; fainting; dizziness or lightheadedness; or fast or irregular heartbeat.

Denileukin diftitox may cause vision changes, including blurred vision, loss of vision, and loss of color vision. Vision changes may be permanent. If you experience any changes in vision call your doctor immediately.

Keep all appointments with your doctor and the laboratory. Your doctor will order certain tests to check your body’s response to denileukin diftitox.

Denileukin diftitox is used to treat cutaneous T-cell lymphoma (CTCL, a group of cancers of the immune system that first appear as skin rashes) in people whose disease has not improved, has gotten worse, or has come back after taking other medications. Denileukin diftitox is in a class of medications called cytotoxic proteins. It works by killing cancer cells.

Denileukin diftitox comes as a solution (liquid) to be injected over 30 to 60 minutes intravenously (into a vein). Denileukin diftitox is administered by a doctor or nurse in a medical office or infusion center. It is usually given once a day for 5 days in a row. This cycle may be repeated every 21 days for up to eight cycles.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

Before taking denileukin diftitox,

• tell your doctor and pharmacist if you are allergic to denileukin diftitox or any of the ingredients in denileukin diftitox. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding.

Unless your doctor tells you otherwise, continue your normal diet.

If you miss an appointment to receive a dose of denileukin diftitox, call your doctor right away.

Denileukin diftitox, may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• nausea
• vomiting
• diarrhea
• loss of appetite
• change in ability to taste
• feeling tired
• pain, including back, muscle, or joint pain
• cough
• headache
• weakness
• rash
• itching

Some side effects can be serious. If you experience any symptoms listed in the IMPORTANT WARNING section, call your doctor immediately.

Denileukin diftitox may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

This medication will be stored at your doctor’s office or clinic.

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, immediately call emergency services at 911.

Symptoms of overdose may include the following:

• nausea
• vomiting
• fever
• chills
• weakness

Ask your pharmacist any questions you have about denileukin diftitox.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

• Ontak^®