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Maintenance Rituximab May Prolong Progression-Free Survival and Response Rates in Previously Untreated Follicular Lymphoma: Presented at NHL

By Chris Berrie

PRAGUE, CZECH REPUBLIC -- September 15, 2004 -- Maintenance rituximab appears to significantly prolong progression-free survival (PFS) and improves response rates following cyclophosphamide/vincristine/prednisone (CVP) induction in patients with previously untreated follicular lymphoma (FL).

The findings, from a randomised phase 3 trial conducted by the Eastern Cooperative Oncology Group (ECOG 1496) in collaboration with the Cancer and Leukaemia Group B (CLGB), were presented here September 11^th at The Role of Immunotherapy in NHL: Optimising Treatment Outcomes, sponsored by Roche.

The course of FL progression involves chronic relapses and remission. The researchers' aim in designing their study was therefore to improve PFS to administer chemotherapy induction to maximum benefit, followed by a maintenance regimen of rituximab, said Theresa Ryan, MD, assistant professor, department of Medicine, division of oncology, New York University Medical Center, New York, New York, United States, who presented the study results.

The study originally compared CVP with a combination of cyclophosphamide and fludarabine (CF) as induction therapy, with a planned second randomisation to rituximab maintenance versus observation in patients who achieved response or stable disease. Following the initial toxicity analysis, the CF arm was stopped, and the trial was modified to compare rituximab with observation after CVP chemotherapy.

A total of 409 patients were treated with 6 to 8 cycles of CVP, consisting of cyclophosphamide 1 g/m² plus vincristine 1.4 mg/m² on day 1, and prednisone 100 mg/m² on days 1 to 5. Objective response or stable disease was achieved in 322 patients (78.7%), who were then randomised to rituximab 375 mg/m² weekly for 4 weeks every 6 months for 2 years or observation.

There were 305 patients who completed treatment and were evaluable for response; these were stratified by extent of residual disease and histology. The characteristics were well balanced between the 157 patients in the rituximab arm and the 148 in the observation arm. There were also no significant differences in grade 3/4 toxicity between rituximab maintenance and observation.

The response rates following CVP induction and randomisation showed no significant differences between the 2 arms, as would be expected, Dr. Ryan said. R-CVP, however, resulted in an additional 28 responses (22%), including an increase from 14% to 30% in complete response rates, she added. This was statistically significant in comparison with the 8% increase in responses in the observation arm (P =.002).

Median PFS from maintenance randomisation for rituximab versus observation was 4.2 years versus 1.5 years, with the 2-year PFS at 74% and 42% (P =.00003), respectively. Following a subset analysis, the median PFS for patients with a follicular histology was not reached in the 121 patients treated with rituximab compared with 1.5 years for the 117 patients in the observation arm, with the 2-year PFS at 71% versus 41% (P =.0002), respectively. Similarly, the 2-year overall survival (OS) after randomisation was significantly higher for patients with follicular histology (96% vs 86%, P =.02). The high tumour burden subset showed similar data for rituximab versus observation (PFS, 71% vs 33%, P =.001; OS, 96% vs 83%, P =.04, respectively), and the minimal residual disease subset also showed a good PFS benefit (85% vs 47%, P =.0001, respectively).

Dr. Ryan stressed in particular the benefit of rituximab in PFS in these subsets, and noted that the improvements in total group overall survival rate did not reach significance (P =.06), probably due to the few events to date.


[Presentation title: Rituximab Maintenance Therapy After Chemotherapy Induction. Abstract 537]

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