Maintenance Rituximab Post Bendamustine/Rituximab in FL

Is the continuation of maintenance rituximab beneficial post bendamustine plus rituximab treatment in FL Patients?

After experiencing partial response on bendamustine plus rituximab, medically fit patients with follicular lymphoma who continued on maintenance rituximab had prolongation of remission with an acceptable safety profile, according to a retrospective analysis.

There is currently a lack of data demonstrating a benefit for giving maintenance rituximab after front-line bendamustine/rituximab in these patients. In addition, the recently published GALLIUM study, which compared bendamustine/rituximab with bendamustine/obinutuzumab followed by either rituximab or obinutuzumab maintenance showed a high rate of fatal adverse events in patients treated with bendamustine/rituximab with rituximab maintenance.

“In the setting in which a randomized prospective trial is unlikely to be conducted, retrospective analysis can offer important insights into real-world patient outcomes and potentially inform practice decisions as well as future clinical trial designs,” Brian T. Hill, MD, of Cleveland Clinic, and colleagues wrote in the British Journal of Haematology. “These data suggest that maintenance rituximab after bendamustine/rituximab is safe.”

Hill and colleagues used data from multiple institutions on 640 patients with newly diagnosed follicular lymphoma. Of these patients, 410 had responses to induction therapy, including 262 with complete remission and 114 with partial remission.

The 3-year progression-free survival was 84.2% for maintenance rituximab compared with 61.2% for no maintenance (P < .001) and overall survival was 94.3% compared with 85.1%, respectively (P = .001).

Improved duration of remission (DOR) was seen in patients who achieved partial remission after four or more cycles of bendamustine/rituximab and continued with maintenance rituximab compared with no maintenance therapy (80% vs 45%; P = .003). However, this was not true of patients who achieved complete remission (3-year DOR: 85.9% vs 80.2%; P = .535).

“The DOR benefit appeared to be more robust for PR patients with high baseline FLIPI [Follicular Lymphoma International Prognostic Index] risk as compared to low FLIPI as well as those with PR as determined by CT scan (vs PET), but these findings should be interpreted with caution due to the small numbers of patients in each subgroup,” the researchers wrote.

The researchers confirmed these overall survival findings in a validation cohort of 207 patients treated with bendamustine/rituximab seen at the MD Anderson Cancer Center.

In all 640 patients, the rate of fatal adverse events at 3 years was 9.8%; known causes of death were from multi-organ system failure, cardiovascular events, myelodysplastic syndrome, respiratory failure, and progressive multifocal leukoencephalopathy. Excluding cases of unknown cause of death and death from solid tumors, this was a known fatal adverse event rate of 2.5%. The rate of known fatal adverse events was similar between those assigned to maintenance rituximab (2.2%) and no maintenance (3.2%).