Dr. Mathias J. Rummel
Mathias J. Rummel, MD, PhD, of Universitaetsklinik, presented these results (Abstract 7503) during the “Hematologic Malignancies—Lymphoma and Chronic Lymphocytic Leukemia” Oral Abstract Session on June 5.
“Maintenance rituximab did not improve progression-free or overall survival after bendamustine/rituximab,” Dr. Rummel said. “We showed no statistical evidence supporting benefit of rituximab maintenance in elderly patients with mantle cell lymphoma following induction with bendamustine/rituximab.”
According to Dr. Rummel, previous research has demonstrated that bendamustine plus rituximab is an effective treatment in patients with mantle cell lymphoma. However, the use of rituximab for maintenance therapy in these patients is not yet common practice, and there are no data available for the use of rituximab after bendamustine/rituximab.
This subgroup study enrolled 168 patients with mantle cell lymphoma who were not eligible for stem cell transplantation and treated them with up to six cycles of bendamustine/rituximab. Responding patients were randomly assigned to observation (62 patients) or rituximab maintenance (60 patients) every 2 months for 2 years. The median age of patients was 71.
After induction treatment with bendamustine/rituximab the overall response rate was 85%, with 27% of patients achieving a complete response and 58% of patients achieving a partial response.
After a median follow-up of 58.4 months, the median progression-free survival for all 168 patients initially registered in the trial was 64.2 months. For the 106 patients treated with bendamustine/rituximab alone—including non-responders who were excluded from randomization and patients assigned to observation—the median progression-free survival was 43.2 months.
Dr. Jonathan W. Friedberg
Similarly, although the median overall survival for patients assigned to observation or maintenance rituximab was not yet reached, at 58 months follow-up there was no statistically significant difference between the two treatment arms (HR 1.51, 95% CI [0.70, 3.25]).
There were 15 deaths in the maintenance therapy arm (10 from lymphoma, four from infection, and one suicide), and there were 11 deaths in the observation arm (two from lymphoma, two from infection, three from cardiac reasons, one from a secondary malignancy, one accidental death, and two unknown).
During his discussion of these results, Jonathan W. Friedberg, MD, of the University of Rochester, emphasized that rituximab has had a significant effect on the treatment of various types of non-Hodgkin lymphoma, including improving overall survival in diffuse large B-cell and follicular lymphomas, and has prolonged remission duration in follicular, mantle cell, and marginal zone lymphomas.
However, he questioned whether more rituximab is always better.
Given the length of the study’s follow-up period, “it is very unlikely that you will see an impact on overall survival, particularly because the observation group, if anything, is doing a bit better than the rituximab maintenance group,” Dr. Friedberg said. “Based on the data today, there is no clear role for rituximab as maintenance after bendamustine/rituximab induction in mantle cell lymphoma in responding patients.
“These negative results with rituximab should have implications on studies of prolonged treatment strategies incorporating other novel agents, including very expensive novel agents as well,” he added. “I think it should give us pause in the design of those studies to look at appropriate endpoints.”