ORLANDO, Florida—Conventional chemotherapy has limited efficacy against follicular non-Hodgkin’s lymphoma (NHL), but research reported at the 43rd Annual Meeting of the American Society of Hematology showed promising results when conventional regimens were combined with the anti-CD20 drug tositumomab/I-131 tositumomab (Bexxar).
Oliver W. Press, MD, reported for the Southwest Oncology Group on SWOG-9911, a phase II trial of CHOP (cyclophosphamide [Cytoxan, Neosar], doxorubicin HCl, vincristine [Oncovin], prednisone) followed by tositumomab/I-131 tositumomab for newly diagnosed follicular non-Hodgkin’s lymphomas. John P. Leonard, MD, reported a trial of fludarabine (Fludara) followed by tositumomab/I-131 tositumomab for follicular low-grade lymphoma.
CHOP Followed by Radioimmunotherapy
"Advanced follicular lymphomas are incurable with conventional chemotherapy regimens. Standard chemotherapy and radiolabeled antibodies each cause remission but are not curative, so we decided to try combining these modalities," Dr. Press said. He is professor of medicine in the Department of Medical Oncology at the University of Washington in Seattle.
Patients were treated with six cycles of standard CHOP chemotherapy (cyclophosphamide at 750 mg/m², doxorubicin at 50 mg/m², vincristine at 1.4 mg/m², and prednisone at 100 mg orally for 5 days) given at 3-week intervals followed by radioimmunotherapy. Four weeks after the completion of the last cycle of CHOP, patients with either a partial (PR) or complete remission (CR) underwent dosimetry with 450 mg of unlabeled tositumomab and 35 mg of trace-labeled I-131 tositumomab. Based on the rate of clearance of this dosimetric infusion, the subjects were treated with tositumomab labeled with 48 to 115 mCi of I-131 (median: 84 mCi), estimated to deliver 75 cGy to the whole body. This therapeutic dose was administered 1 to 2 weeks after the trace-labeled dose.
Toxicity and Response Data
Dr. Press said that 102 patients with newly diagnosed follicular lymphomas (grade 1, 2, or 3) were registered, of whom 92 were eligible for treatment. Eighty-eight patients were evaluable for toxicity from the CHOP regimen; 60 patients were evaluable for toxicity from I-131 tositumomab. This included grade 3 or 4 neutropenia in 52% of patients after CHOP and 15% of patients after I-131 tositumomab; thrombocytopenia in 1% and 15%; and febrile neutropenia in 7% and 3%.