Coulter Pharmaceutical -
[Cached Version]
Published on: 10/20/1997
Last Visited: 9/13/2000
The preliminary data were generated from 15 patients of a planned 78-patient randomized, controlled Phase II clinical trial and were presented by Susan Knox, M.D., Ph.D., associate professor, Radiation Oncology at Stanford University Medical Center and a principal investigator for the clinical trial.
The trial is being conducted in low-grade, non-Hodgkin's lymphoma patients with chemotherapy refractory NHL who have progressed within one year after completing their last chemotherapy regimen.Patients are randomized 1 : 1 to receive either Bexxar therapy or the unlabeled monoclonal antibody specific for the CD20 antigen found on NHL cells.
Dr. Knox reported that 75 percent (six of eight) of the patients randomized to the Bexxar arm responded to the therapy, compared to only 43 percent (three of seven) of patients who responded to the unlabeled antibody.Two of the patients in the Bexxar arm experienced a complete remission of their disease while only one patient in the unlabeled antibody arm achieved a complete remission.
While follow-up is limited in this preliminary report, the longest time to progression for Bexxar-treated patients was nine months (ongoing) compared to five months with that for unlabeled antibody-treated patients.Follow-up evaluation will be conducted to confirm all responses.Both treatments were well-tolerated with the only significant toxicity being temporary and reversible myelosuppression.
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Dr. Knox commented, The results in the unlabeled antibody arm are fairly consistent with previous results reported with the use of unmodified anti-CD20 antibodies for the treatment of non-Hodgkin's lymphoma.Though the trial is still ongoing, the results do indicate a trend toward more durable complete remissions and a higher overall response rate using radiolabeled Bexxar in treating non-Hodgkin's lymphoma.For this reason, the trial allows patients randomized to the unlabeled antibody arm to crossover to the Bexxar arm following disease progression.Data from these crossover patients are still being generated..
Bexxar, which is an antibody radiolabeled with iodine-131 (I131), attaches to a protein found only on the surface of B-cells, both non-Hodgkin's lymphoma B-cells and some normal B-cells.Through this targeted approach, the tumor cells receive a higher dose of the therapeutic radiation from Bexxar relative to normal tissues.