Bendamustine, Bortezomib, and Rituximab in Patients with Previously Untreated Low Grade Lymphoma: A Phase II Trial of the Sarah Cannon Research Institute

Rituximab and bendamustine combination regimens have demonstrated high activity in non-Hodgkin's lymphoma (NHL). A phase III trial compared bendamustine plus R-CHOP as first-line treatment for follicular, indolent, and mantle cell lymphoma (Rummel ASH 2009). Bendamustine plus rituximab had an overall response rate of 94% and a complete remission rate of 40% compared to 94% and 31%, respectively, for R-CHOP. Phase III trials evaluating bendamustine plus rituximab as first-line therapy for patients (pts) with indolent and mantle cell lymphoma have shown equivalent or superior results when compared to R-CHOP or R-CVP as first-line treatment for indolent lymphoma. Bortezomib is a small molecule proteasome inhibitor that has shown substantial activity in multiple myeloma and lymphoma. Pre-clinical studies demonstrate significant synergy and/or ability to overcome resistance to a variety of current and investigational treatments for lymphoma. This trial evaluated the activity of bendamustine, bortezomib, and rituximab (BBR) in patients with previously untreated low-grade lymphoma.

Eligible patients had histologically-confirmed follicular center cell (FCC) lymphoma (grade 1 or 2), marginal zone lymphoma (MZL), small lymphocytic lymphoma (SLL), or lymphoplasmacytic lymphoma (LPL); lymph node biopsy containing CD20+ B-cells; Ann-Arbor Stage 2, 3, or 4 disease; no previous systemic treatment for lymphoma; bi-dimensional measurable disease with at least 1 lesion measuring > 2.0 cm in a single dimension; ECOG PS 0–2. Treatment for all patients was given in 28-day cycles for a maximum of 6 cycles. Patients received rituximab 375 mg/m² IV on days 1, 8, and 15 of cycle 1 (cycles 2–6, rituximab only on day 1); bendamustine 90 mg/m² IV on days 1 and 2; and bortezomib 1.6 mg/m²IV on days 1, 8, and 15. Response evaluations were performed after cycle 3 and cycle 6. Patients were permitted to begin maintenance treatment with rituximab 6 months after completion of study treatment and after 6-month follow-up assessments have been conducted.

Between 1/2010 and 11/2011, 55 patients were enrolled with a median age of 62 years (range 30–89). Fifty one percent were male, 85% stage III or IV. Diagnoses were: FCC, 38pts (69%); MZL, 8pts (15%); SLL, 5pts (9%) and LPL, 4pts (7%). The median follow-up is 13 months (range: 6–26). At the time of this analysis, 78% of pts had completed 6 cycles of BRR, and 56% had continued to maintenance rituximab. Two pts remain in the first 6 cycles of BRR. Five pts (9%) discontinued treatment due to toxicity (1pt G2 neuropathy, 1 pt G2 atrial fibrillation, 1 pt G3 pancreatitis, 1 pt G3 diarrhea, 1pt G2 rash). The remaining 5 pts discontinued prematurely (1pt death due to stroke, 1pt wound complication, 1 pt lost to follow-up, 2 pts off due to request). Objective response was achieved in 89% of pts; 26pts (47%) complete response, 23pts (42%) partial response, 2pts (4%) stable disease, and 4pts (7%) unevaluable at the time of this analysis. Related grade 3/4 hematologic toxicities were: neutropenia (25%), febrile neutropenia (2%), thrombocytopenia (5%), and anemia (4%). We observed no grade 4 treatment related non -hematologic adverse events, the most common grade 3 were neuropathy (9%), diarrhea (7%), fatigue (7%), constipation (5%), and rash (5%). Time-to-event data are immature and will be the subject of a later analysis. At the time of data cut-off, 3 pts (5.5%) had progressed or relapsed and 3pts (5.5%) had died.

BBR was well tolerated and produced high CR and OR rates. Toxicities including neuropathy were modest. Further study of this regimen in patients with previously untreated lymphoma is warranted.

Off Label Use: Off-label bendamustine and bortezomib in first-line treatment for lymphoma. Boccia:Cephalon: Research Funding.