GSK updates long-term survival data of BEXXAR Therapeutic Regimen for Non-Hodgkin's lymphoma

GlaxoSmithKline announced today updated long-term survival data from two Phase II studies of BEXXAR® (tositumomab and iodine I-131 tositumomab) used in either patients with previously untreated cancer of the immune system (follicular lymphoma) or in patients with cancer of the lymphocytes (non-Hodgkin's lymphoma, NHL) that no longer responded to rituximab.

The first study demonstrated that, among 76 patients with previously untreated follicular lymphoma, the 10-year overall survival rate was 83% and the 10-year progression-free survival rate was 38%. The second study demonstrated that after long term follow-up, heavily pre-treated, rituximab-refractory patients with NHL experienced an overall survival of 6.7 years (median).

These data were presented at the 51st Annual Meeting of the American Society of Hematology.

"Non-Hodgkin's lymphoma is a serious disease, Non-Hodgkin's lymphoma with more than 65,000 estimated new cases in 2009. These data are exciting because they continue to support that BEXXAR has the potential to provide clinical benefit that translates to long-term survival - ultimately supporting our number one goal of helping patients," said Jeffrey Bloss, MD, Vice President, North American Medical Affairs, GSK Oncology.

The complete prescribing information for BEXXAR contains the following black boxed warnings: hypersensitivity reactions, including anaphylaxis; prolonged and severe cytopenias; pregnancy category X; and special requirements related to the radioactive component of the product. Additional important safety information is provided below and can be found in the complete prescribing information for BEXXAR.

For previously untreated follicular lymphoma: Abstract #3759

In addition to the 10-year overall survival rate of 83%, results showed that the 97% of patients had a response. The overall confirmed response rate was 95%, with 75% of patients in the trial achieving a complete response. The median duration of a complete response was 9.1 years. Finally, the median amount of time follicular lymphoma was responsive to BEXXAR therapy was 6 years.

"Across ten years, we are seeing a consistent result and effect on survival by treating patients with BEXXAR first. Rarely are there data to show a treatment can produce a durable response over a decade, and what's most exciting is that these results were achieved after a single treatment," said Mark Kaminski, MD, Professor of Internal Medicine and Director, Leukemia/Lymphoma Program at the University of Michigan and lead investigator of the study.

This was a single center, single-arm, Phase II trial of previously untreated patients>

Five patients (7%) were managed with thyroid hormone replacement therapy from 0.5 to 2.9 years after treatment. Eleven patients (14%) were diagnosed with second malignancies. Malignancies included 4 skin neoplasms (2 basal cell and 2 squamous cell) and 7 visceral neoplasms (3 breast, 2 prostate, 1 endometrial cancer, 1 glioblastoma). In addition, one case of myelodsyplastic syndrome was diagnosed about 8 years after treatment. Hematologic toxicity was common, with grade 4 neutropenia in 5% of patients and no grade 4 thrombocytopenia.

The five-year follow-up data from this study were originally reported in the New England Journal of Medicine in 2005 (NEJM 352:441, 2005). Eight year follow-up data were presented at ASCO 2007.

For non-Hodgkin's lymphoma patients who progressed after treatment with rituximab: Abstract #2732

In addition to the median overall survival of 6.7 years, 72% of patients experienced a response. The overall confirmed response rate was 65% and the complete response rate was 38%. The amount of time patients maintained a response to therapy was 18.9 months (median), with an estimated 40% of patients maintaining a response at five years. There were only two known relapses after two years. Additionally, patients experienced a median of 10.4 months without disease progression, with 28% of patients remaining progression-free at approximately five years.

"It is encouraging to see such long-term durable responses in one of the original patient populations, demonstrating the activity of BEXXAR in patients with rituximab-refractory disease," said Anas Younes, MD, the University of Texas M.D. Anderson Cancer Center. "These results suggest a long-term therapeutic value of BEXXAR for patients with rituximab-refractory, indolent lymphoma."

This study evaluated long-term safety and efficacy data from a Phase II study of patients with slow-growing, follicular large-cell or transformed B-cell lymphoma, which was progressive after rituximab>

To date, 20 deaths have been reported, 10 without documented disease progression. Six second cancers have occurred: 2 acute leukemia, 1 prostate, 2 skin (1 squamous, 1 Merkel cell), and 1 primary hepatic. The incidence of secondary leukemia remains the same as previously reported in 2005 at 5% (2 of 40 patients). Seven of the 40 patients enrolled in this study had elevated thyroid stimulating hormone (TSH) levels prior to receiving the therapeutic dose of iodine-131 tositumomab and 2 patients did not have baseline TSH data. Of the 31 patients with normal baseline TSH levels prior to treatment, 3 developed elevated TSH as of July 2009 and as reported previously. There were no cases of hypothyroidism reported as an adverse event by investigators as of July 2009.

These data were previously reported in the Journal of Clinical Oncology in 2005 (J Clin Oncol 23:712, 2005).




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