ORLANDO, Fla.—For older patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) who are not transplant candidates or may not tolerate aggressive therapy with its associated higher toxicity, bendamustine (B) plus rituximab (R) may have a treatment role, results of an ongoing study suggest.
Preliminary results based on efficacy data from 33 evaluable subjects to date have demonstrated an overall response rate of 51.6%, with 5 patients (15.2%) achieving a complete response and 12 patients a partial response (36.4%), reported Jeffrey Vacirca, MD, North Shore Hematology/Oncology Associates, East Setauket, New York, and colleagues. Seven of the remaining patients (21.2%) had stable disease and 9 (27.2%), disease progression.
Bendamustine has shown activity as a single agent and in combination therapy for indolent lymphomas; however, data on activity in DLBCL and other aggressive lymphomas have been limited. While current first-line immunochemotherapy for DLBCL is highly effective, those ineligible for transplant or who relapse after transplant have a poor prognosis. Aggressive salvage regimens are frequently intolerable and may require patients to be hospitalized. Based on the favorable toxicity profile and demonstrated synergy of bendamustine with rituximab, the safety and efficacy of this BR combination are being studied in patients with relapsed or refractory DLBCL, the investigators noted in a poster presentation during the 52nd American Society of Hematology Annual Meeting and Exposition.
Patients with DLBCL who had failed at least one prior therapy and at least one measurable lesion received bendamustine 120 mg/m2 days 1 and 2 and rituximab 375 mg/m2 day 1 every 28 days for up to 6 cycles. A Simon two-stage design (a=0.1, b=0.2, P0=50%, P1=70%) allowed the study to continue until 43 patients in the modified intent-to-treat (mITT) population were evaluable for efficacy only if at least 8 of the first 15 patients enrolled achieved a complete or partial response and had received at least one response evaluation. Safety is being assessed weekly. Disease status, as measured by the Revised Response Criteria for Malignant Lymphoma, is evaluated after every 2 cycles is completed.
Median age of the 43 patients currently enrolled is 74 years (range, 54-90 years), with the majority having an ECOG performance status at baseline of 0 or 1 (95%). Conversely, the majority (70%) had a baseline Revised International Prognostic Index score of poor. A median of 3 cycles per subject has been administered. Four patients were removed from the study before the first efficacy evaluation; 3 withdrew consent prior to cycle 1, and one had disease progression during cycle 1. An additional 4 patients had not completed their first efficacy evaluations. Overall response rate in the mITT population was 55% with 7 complete responders (18%), 15 partial responders (37%), 9 patients (23%) with stable disease and 9 patients (23%) with progressive disease.
Grade 3/4 hematologic adverse events included anemia (n=4), leucopenia (n=6), neutropenia (n=15), and thrombocytopenia (n=4). Other treatment-related grade 3/4 adverse events included hepatic failure (n=1), disseminated herpes zoster (n=1), diarrhea (n=1), elevated liver functions (n=1), mucositis (n=1), dehydration (n=1), anorexia (n=1), and weight loss (n=1). Grade 1/2 adverse events were consistent with treatment and anticipated comorbidities of the population with DLBCL.