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Care During Chemotherapy and Beyond

Tositumomab

Tositumomab
(toe-si-TYOO-mo-mab)

Trade name: Bexxar®
Other name: Tositumomab and Iodine I - 131

Chemocare.com uses generic names in all descriptions of drugs. Bexxar is the trade name for Tositumomab. Tositumomab and Iodine I - 131 is another name for Tositumomab. In some cases, health care professionals may use the trade name Bexxar or other name Tositumomab and Iodine I - 131 when referring to the generic drug name Tositumomab.

Drug type: Tositumomab is a monoclonal antibody that is linked with a radioactive atom Iodine - 131. (For more detail, see "How this drug works" section below.)

What Tositumomab Is Used For:

  • Treatment of certain types of non-Hodgkin's lymphomas that have recurred after, or have not responded to prior treatment.

Note:  If a drug has been approved for one use, physicians may elect to use this same drug for other problems if they believe it may be helpful.

How Tositumomab Is Given:

  • Infusion into a vein (intravenous, IV).
  • Given only as a two step protocol, the dosimetric step and the therapeutic step.  Each step consists of an infusion of Tositumomab followed by Iodine I 131 linked to a molecule of Tositumomab.
  • Step 1 - (dosimetric step), this step is performed in order to determine how the medication is distributed through the body.  The infusion is followed by scans done within 1 hour, 2-4 days and at 6-7 days.
  • The amount of the therapeutic dose of Iodine I 131 Tositumomab that you will receive is calculated based on data obtained from the scans.
  • Step 2 - (therapeutic step), 7-14 days following Step 1, Tositumomab infusion followed by Iodine I 131 linked to Tositumomab.
  • You will be given a prescription for medication to protect your thyroid gland.  This medication is to be started at least 24 hours before the first step of the protocol, and will continue until about 2 weeks after the second step (therapeutic dose).  The dose of this medication is adjusted for each individual patient.  Note * You will not be able to be treated with tositumomab if you do not take the thyroid protection medication 24 hours prior to the time you are scheduled for treatment.  (see Precautions)

Side Effects:

Important things to remember about the side effects of Tositumomab:

  • Most people do not experience all of the side effects listed.
  • Side effects are often predictable in terms of their onset and duration.
  • Side effects are almost always reversible and will go away after treatment is complete.
  • There are many options to help minimize or prevent side effects.
  • There is no relationship between the presence or severity of side effects and the effectiveness of the medication. 

The following side effects are common (occurring in more than 30%) for patients taking tositumomab:

  • Low blood counts.  Your white and red blood cells and platelets may temporarily decrease.  This can put you at increased risk for infection, anemia and/or bleeding.  (This effect may be delayed or prolonged for several weeks after treatment is given).

Nadir:  Meaning low point, nadir is the point in time after treatment in which you experience low blood counts.

  • Time to nadir: 4-7 weeks
  • Duration of nadir: approximately 30 days,
            (in a small number of patients can be more than 90 days)
  • Fever
  • Weakness

These are less common side effects (occurring in 10-29%) for patients receiving tositumomab:

  • Infusion related reactions (occurred within 14 days of infusion, including bronchospasm, chills, shortness of breath, fever, low blood pressure, nausea, shaking chills, sweating)
  • Infection
  • Cough, throat irritation
  • Pain
  • Hypothyroidism
  • Rash
  • Headache
  • Abdominal pain
  • Vomiting
  • Poor appetite
  • Diarrhea
  • Itching
  • Generalized aches and pains (myalgias & arthralgias)
  • Runny nose

Not all side effects are listed above. Some that are rare (occurring in less than 10% of patients) are not listed here.  However, you should always inform your health care provider if you experience any unusual symptoms.

When to contact your doctor or health care provider:

Contact your health care provider immediately, day or night, if you should experience any of the following symptoms:

  • Fever of 100.4° F (38° C) or higher, chills (signs of possible infection)
  • Shortness of breath, chest pain or discomfort; swelling of your lips or throat
  • Confusion

The following symptoms require medical attention, but are not an emergency.  Contact your health care provider within 24 hours of noticing any of the following:

  • Nausea (interferes with ability to eat and unrelieved with prescribed medication).
  • Vomiting (vomiting more than 4-5 times in a 24 hour period).
  • Diarrhea (4-6 episodes in a 24-hour period).
  • Unusual bleeding or bruising.
  • Black or tarry stools, or blood in your stools or urine.
  • Extreme fatigue (unable to carry on self-care activities).

Always inform your health care provider if you experience any unusual symptoms.

Precautions:

  • Protecting your thyroid: Your thyroid gland produces chemicals your body needs to function properly.  To do do, your thyroid absorbs iodine from your blood stream.  Because the isotope attached to tositumomab is a radioactive form of iodine, it is important to protect your thyroid from absorbing it.  You will be given a prescription for medication to protect your thyroid gland.  This medication is to be started at least 24 hours before the first step of the protocol, and will continue until about 2 weeks after the second step (therapeutic dose).  The dose of this medication is adjusted for each individual patient. 
  • Before starting tositumomab treatment, make sure you tell your doctor about any other medications you are taking (including prescription, over-the-counter, vitamins, herbal remedies, etc.).   Do not take aspirin, products containing aspirin unless your doctor specifically permits this.
  • Do not receive any kind of immunization or vaccination without your doctor's approval while taking tositumomab.
  • Inform your health care professional if you are pregnant or may be pregnant prior to starting this treatment. Pregnancy category X (tositumomab can cause fetal harm when administered to a pregnant woman).
  • For both men and women: Do not conceive a child (get pregnant) while taking tositumomab, and for 12 months following the administration of this therapeutic regimen.   Discuss with your doctor when you may safely become pregnant or conceive a child after therapy.
  • Do not breast feed while taking this medication.

Self-Care Tips:

  • You may be at risk of infection so try to avoid crowds or people with colds or not feeling well, and report fever or any other signs of infection immediately to your health care provider.
  • Wash your hands often.
  • Use a soft toothbrush to minimize bleeding.
  • Avoid contact sports or activities that could cause injury.
  • To reduce nausea, take anti-nausea medications as prescribed by your doctor, and eat small, frequent meals.
  • In general, drinking alcoholic beverages should be kept to a minimum or avoided completely.  You should discuss this with your doctor.
  • Get plenty of rest.
  • Maintain good nutrition.
  • If you experience symptoms or side effects, be sure to discuss them with your health care team.  They can prescribe medications and/or offer other suggestions that are effective in managing such problems.

Radiation Safety: 

  • While the Iodine- I 131 in Iodine I 131 tositumomab is in the body, a person will be "giving off" a small amount of low-level radiation.   This amount will be less and less as time goes by.
  • The Iodine-131 is removed from the body by the kidneys, so most of the radioactivity leaves the body through urine over about a week.
  • For a short time after treatment with  Iodine I 131 tositumomab lifestyle adjustments will be necessary (2 weeks or less).  This is to make sure family members and the people taking care of you are exposed to as little radiation as possible.
  • Lifestyle changes that will help protect others:
    • Sleep in a separate bed (at least 6 feet from anyone else)
    • Do not take a long trip (4 hours or more) sitting near others (eg, car, train, airplane, bus)
    • Stay at least 6 feet from children and pregnant women
    • Minimize time spent near others and delay return to work
    • Keep at least 6 feet from others whenever possible
    • When taking shorter trips, sit as far as possible from others
    • Do not let others use your bathroom, if possible
    • Menstruating women should use tampons that can be flushed down the toilet.
    • Sit while urinating and flush the toilet 3 times with the lid down
    • Wash hands often, including after each toilet use, and shower daily
    • Drink plenty of liquids (two to three quarts of fluid for the first 48 hours)
    • Use separate towels, washcloths, and toothbrush from rest of household members
    • Use separate dishes and utensils for 1 week and wash separately
    • Hold clothing and linen (sheets and towels) for 1 week before laundering and launder separately form rest of household's laundry
    • Avoid using disposable items that cannot be flushed down the toilet

Monitoring and Testing:

You will be checked regularly by your healthcare professional after taking tositumomab, to monitor side effects and check your response to therapy.  Periodic blood work to monitor your complete blood count (CBC), the function of other organs (such as your kidneys and liver), as well as your thyroid gland function will also be ordered by your doctor.  

How Tositumomab Works:

Tositumomab is classified as a monoclonal antibody.  Monoclonal antibodies are a relatively new type of "targeted" cancer therapy.

Antibodies are an integral part of the body's immune system.  Normally, the body creates antibodies in response to an antigen (such as a protein in a germ) that has entered the body.  The antibodies attach to the antigen in order to mark it for destruction by the immune system.

To make anti-cancer monoclonal antibodies in the laboratory, scientists analyze specific antigens on the surface of cancer cells (the targets).  Then, using animal and human proteins, they create a specific antibody that will attach to the target antigen on the cancer cells. When given to the patient, these monoclonal antibodies will attach to matching antigens like a key fits a lock.

Since monoclonal antibodies target only specific cells, they may cause less toxicity to healthy cells.   Monoclonal antibody therapy is usually given only for cancers in which antigens (and the respective antibodies) have been identified already.

Tositumomab works by targeting the CD20 antigen on normal and malignant B-cells. However, it is more than a monoclonal antibody alone.  In the laboratory, a radioactive substance (Iodine I 131) is linked to the antibody.  When the antibody attaches to the CD20 antigens, radiation is delivered directly to the targeted cells, killing the targeted cells as well as cancer cells in the immediate area.  Stem cells (young cells in the bone marrow that will develop into the various types of cells) do not have the CD20 antigen.  This allows healthy B-cells to regenerate after treatment.  This type of therapy is also known as radioimmunotherapy.

Note:  We strongly encourage you to talk with your health care professional about your specific medical condition and treatments. The information contained in this website is meant to be helpful and educational, but is not a substitute for medical advice. 

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