Bendamustine therapy in patients with relapsed or refractory Waldenström's macroglobulinemia.

We report the treatment outcome for 30 relapsed/refractory Waldenström's macroglobulinemia (WM) patients following bendamustine-containing therapy. Treatment consisted of bendamustine (90 mg/m2 I.V. on days 1, 2) and rituximab (375 mg/m2 I.V. on either day 1 or 2) for 24 patients. Six rituximab-intolerant patients received bendamustine alone (n=4) or with ofatumumab (1000 mg I.V. on day 1; n=2). Each cycle was 4 weeks, and median number of treatment cycles was 5. At best response, median serum IgM declined from 3980 to 698 mg/dL (P<.0001), and hematocrit rose from 31.9% to 36.6% (P=.0002). Overall response rate was 83.3%, with 5 VGPR and 20 PR. The median estimated progression-free survival for all patients was 13.2 months. Overall therapy was well tolerated. Prolonged myelosuppression was more common in patients who received prior nucleoside analogues. Bendamustine is active and produces durable responses in previously treated WM, both as monotherapy and with CD20-directed monoclonal antibodies.