The BEXXAR Therapeutic Regimen,a Radioimmunotherapy for non-Hodgkin's lymphoma
The BEXXAR therapeutic regimen (Tositumomab and Iodine I 131 Tositumomab) is indicated for the treatment of patients with CD20 antigen-expressing relapsed or refractory, low-grade, follicular, or transformed non-Hodgkin’s lymphoma, including patients with Rituximab-refractory non-Hodgkin’s lymphoma.
Determination of the effectiveness of the BEXXAR therapeutic regimen is based on overall response rates in patients whose disease is refractory to chemotherapy alone or to chemotherapy and Rituximab.
The effects of the BEXXAR therapeutic regimen on survival are not known.
The BEXXAR therapeutic regimen is not indicated for the initial treatment of patients with CD20-positive non-Hodgkin’s lymphoma.
The BEXXAR therapeutic regimen is intended as a single course of treatment. The safety of multiple courses of the BEXXAR therapeutic regimen, or combination of this regimen with other forms of irradiation or chemotherapy, has not been eva luated.
Hypersensitivity Reactions, Including Anaphylaxis: Serious hypersensitivity reactions, including some with fatal outcome, have been reported with the BEXXAR therapeutic regimen. Medications for the treatment of severe hypersensitivity reactions should be available for immediate use.
Patients who develop severe hypersensitivity reactions should have infusions of the BEXXAR therapeutic regimen discontinued and receive medical attention (see WARNINGS in Prescribing Information).
Prolonged and Severe Cytopenias: The majority of patients who received the BEXXAR therapeutic regimen experienced severe thrombocytopenia and neutropenia.
The BEXXAR therapeutic regimen should not be administered to patients with >25% lymphoma marrow involvement and/or impaired bone marrow reserve (see WARNINGS and ADVERSE REACTIONS in Prescribing Information).
Pregnancy Category X: The BEXXAR therapeutic regimen can cause fetal harm when administered to a pregnant woman.
Special Requirements: The BEXXAR therapeutic regimen (Tositumomab and Iodine I 131 Tositumomab) contains a radioactive component and should be administered only by physicians and other healthcare professionals qualified by training in the safe use and handling of therapeutic radionuclides.
The BEXXAR therapeutic regimen should be administered only by physicians who are in the process of being or have been certified by GlaxoSmithKline in dose calculation and administration of the BEXXAR therapeutic regimen.
IMPORTANT SAFETY INFORMATION1
Contraindications: The BEXXAR therapeutic regimen (Tositumomab and Iodine I 131 Tositumomab) is contraindicated in patients with known hypersensitivity to murine proteins or any other component of BEXXAR.
BEXXAR is contraindicated for use in women who are pregnant.
Data regarding adverse events were primarily obtained in 230 patients with non-Hodgkin’s lymphoma enrolled in 5 clinical trials.
Data from 765 patients enrolled in an expanded access program were used to supplement the characterization of delayed adverseevents.
Prolonged and Severe Cytopenias: The majority of patients, 71% of 230, who received the BEXXAR therapeutic regimen, experienced severe
or life-threatening (Grade 3/4) cytopenias. The most common were thrombocytopenia (53%) and neutropenia (63%). Time to nadir was 4-7
weeks, lasting approximately 30 days. Due to the variable nature of the onset of the cytopenias, complete blood counts should be obtained weekly for 10-12 weeks. More frequent monitoring is indicated in patients with evidence of moderate or more severe cytopenias.
Blood counts should be monitored weekly until severe cytopenias have resolved. Sequelae included infections (45%), hemorrhage (12%), and requirement for hematological supportive care(27%).
Hypersensitivity Reactions Including Anaphylaxis: Hypersensitivity reactions, including some with fatal outcome, were reported during and following administration of the BEXXAR therapeutic regimen in 6%(14) of 230 patients.
In the postmarketing setting, severehypersensitivity reactions, including fatal anaphylaxis, have been reported. Patients who have received murine proteins should be screened for human anti-mouse antibodies (HAMA) as they may be at increased risk for serious allergic reactions.
Immunogenicity: Administration of BEXXAR may result in the development of HAMA. Of the 230 patients in the clinical studies, 220 patients were seronegative for HAMA prior to treatment, and 219 had at least 1 posttreatment HAMA value obtained.
With a median observation period of 6 months, a total of 23 patients (11%) became seropositive for HAMA posttreatment. The median time of HAMA development was 6 months. The cumulative incidences of HAMA seropositivity at 6 months, 12 months, and 18 months were 6%, 17%, and 21%, respectively. The presence of HAMA may affect the toxicity and/or efficacy of in vivo diagnostic or therapeutic agents that rely on murine antibodies and may affect the accuracy of in vitro and in vivo diagnostic tests.
Secondary Leukemia, Myelodysplastic Syndrome (MDS), and Secondary Malignancies: At a median follow-up of 29 months, 44 cases of myelodysplastic syndrome and/or secondary leukemia were reported in 995 patients enrolled in clinical studies and an expanded access program.
Additional malignancies (65 cases) were also reported in 54 of the patients. Approximately half of these were nonmelanomatousskin cancers (26).
The remainder, which occurred in 2 or more patients, included colorectal cancer, head and neck cancer, breast cancer, lung cancer, bladder cancer, melanoma, and gastric cancer, in order of decreasing incidence.
The relative risk of developing secondary malignancies in patients receiving BEXXAR over the background rate in this population cannot be determined due to the absence of controlled studies.
Hypothyroidism: Administration of BEXXAR may result in hypothyroidism. Of the 230 patients in the clinical studies, 203 patients did not have elevated thyroid-stimulating hormones (TSH) upon study entry. Of these, 137 patients had at least 1 posttreatment TSH value available and were not taking thyroid hormonal treatment upon study entry.
With a median follow-up period of 46 months, the incidence of hypothyroidism based on elevated TSH or initiation of thyroid replacement therapy in these patients was 18%, with a median time to development of hypothyroidism of 16 months. The cumulative incidences of hypothyroidism at 2 and 5 years in these 137 patients were 11% and 19%, respectively. New events have been observed up to 90 months posttreatment.
Of the 765 patients in the expanded access programs, 670 patients did not have elevated TSH upon study entry.
Of these, 455 patients had at least 1 posttreatment TSH value available and were not taking thyroid hormonal treatment upon study entry. With a median follow-up period of 33 months, the incidence of hypothyroidism based on elevated TSH or initiation of thyroid replacement therapy in these 455 patients was 13%, with a median time to development of hypothyroidism of 15 months.
The cumulative incidences of hypothyroidism at 2 and 5 years in these patients were 9% and 17%, respectively.
Thyroid-blocking medication should be prescribed as described in the prescribing information; if patients do not tolerate the medication they should not be given BEXXAR. Patients should be eva luated for signs and symptoms of hypothyroidism and screened for biochemical evidence of hypothyroidism annually.
Infusional Toxicities: Infusional toxicities including fever, rigors, chills, sweating, nausea, hypotension, dyspnea, and bronchospasm have been reported during and/or following the infusion of BEXXAR. Fever, rigors, chills, or sweating were reported in 67 patients (29%) within 14 days following the dosimetric dose.
Infusional toxicities were managed by slowing and/or temporarily interrupting the infusion. Adjustments occurred in 7% of the patients and included reduction in the rate of infusion by 50%, temporary interruption of the infusion, and in 2 patients, infusion was permanently discontinued.
Assessment of Biodistribution: The biodistribution of Iodine I 131 Tositumomab should be assessed. If biodistribution is altered, the therapeutic dose should not be administered.