Information about 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
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

7. Dosing
Schedule

8. CLEARANCE
Average clearance of the drug 68.2 mg/hr
Patients with high tumor burden, splenomegaly, or bone marrow involvement have faster
clearance and shorter terminal half-life
The medial total body effective half-life is 67 hours
Elimination of Iodine – 131 occurs by decay and is excreted in urine
After five days whole body clearance is 67% with 98% of clearance accounted for in urine

9. Physical
Decay Chart
Iodine – 131
T ½ = 8.04 days

10. Storage requirements
Store at 36F to 46F (2o
C – 8o
C) 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

11. 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

12. 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

13. 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

14. 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

16. SIDE EFFECTS
(require immediate medical attention)

17. SIDE EFFECTS
(do not require immediate medical attention)