Pharmacology of Tositumomab

1. Bexxar
(tositumomab)
DARYA OSMAN HUSSEIN

2. GENERAL INFORMATION
Therapeutic class:
Antineoplastic agent
Pharmacologic class:
Monoclonal antibody

3. APPLICATION
Used alone or in combination with iodine I 131
Used to treat CD20-positive, relapsed or refractory non-Hodgkin's lymphoma
Not used for initial treatment of patients with CD20-positive NHL
Used only as a single course of treatment

4. Non-Hodgkin’s
Lymphoma

5. MECHANISM OF ACTION
Binds to the CD20 (human B-lymphocyte restricted differentiation antigen) antigen
This antigen is found on >90% of B-cell NHL
Bexxar acts through:
Addition of ionizing radiation
Induction of apoptosis
Complement dependent cytotoxicity
Antibody-dependent cellular toxicity

6. DOSE AND CLEARANCE
Given as IV solution
Dose for non-Hodgkin's lymphoma is tositumomab 450mg IV infusion over 60 minutes
Follow by I-131 tositumomab dose (calculated to deliver 75cGy total body irradiation for
patients with normal platelet count) for 7 to 14 days
For those with decreased platelet count therapeutic dose adjusted to 65cGy total body
irradiation
Clearance of the drug is 68.2 mg/hr.

7. Storage requirements
Store at 36F to 46F (2oC – 8oC) and protect from strong
light
Thaw directly prior to administration and Do not shake
When diluted tositumomab stable for 24 hours
refrigerated and 8 hours at room temperature
Thawed I131 tositumomab stable for up to 8 hours at
room temperature

8. Dose preparation and disposal
Must be prepared directly before administration
Unused portion and infusion set components must be
discarded according to laws regarding radioactive and
biohazardous waste

9. MONITORING
Monitor for infusion reactions
decreased rate by 50% for mild – moderate reactions
Interrupt infusion for serious reactions and resume at 50% of original if reaction resolves
Monitor for grade 3 or 4 cytopenias up to 3 months after treatment (primarily thrombocytopenia
and neutropenia
Life-long monitoring for hypothyroidism

10. PREGNANCY AND BREASTFEEDING
Pregnancy
High risk to fetus in all trimesters
Males and females should used contraception to prevent
pregnancy during and for 12 months after stopping drug
Breastfeeding:
Harmful to infant

11. PRECAUTIONS
Serious allergic reactions (i.e. anaphylaxis – rash, itching,
fever, chills, light-headedness or dizziness, nausea, trouble
breathing or swelling of hands, face, mouth or throat)
Causes susceptibility to infection (because of temporary
decreased number of WBCs)
Bleeding (due to decreased number of platelets)
May increase chance of certain cancer types or thyroid
problems

13. SIDE EFFECTS
(require immediate medical attention)
Bleeding gums
Bloating or swelling
Blurred vision
Bone pain
Chest pain
Chills
Confusion
Constipation
Coughing up blood
Depression
Difficulty breathing
Difficulty swallowing
Dizziness
Dry skin and hair
Shortness of breath
Skin rash
Slowed heartbeat
Sore throat
Sores or ulcers on mouth
Sweating
Swollen glands
Tightness of hands or feet
Unusual bleeding or bruising
Fast heartbeat
Feeling cold
Hair loss
Headache
Hives
Hoarseness or husky voice
Increased menstrual flow
Itching
Lower back or side pain
Muscle cramps and stiffness
Noisy breathing
Painful or difficult urination
Pale skin
Paralysis
Pinpoint red spots on the skin
Prolonged bleeding from cuts
Puffiness or swelling of eyelids
Rapid weight gain
Red or black tarry stools
Red or dark brown urine
Unusual weight gain or loss
wheezing
Trouble breathing with
exertion

14. Acid or sour stomach
Back pain
Belching
Body aches and pain
Congestion
Difficulty with moving
Heartburn
Indigestion
Itching skin
Joint pain
Lack or loss of strength
Loss of appetite
Loose or liquid stools
Muscle aches or pains
Nausea
Neck pain
Runny nose
Stomach pain
Sudden sweating
Swollen joints
Trouble with swallowing
Voice changes
Vomiting
Weight loss
Sleepiness or drowsiness
Dryness or soreness of throat
Diarrhea or increased bowel
movement
Difficult or labored breathing
Tender, swollen glands in neck
SIDE EFFECTS
(do not require immediate medical attention)