Purpose: Waldenstrom's macroglobulinemia (WM) is a B-cell disorder. Despite advances in the therapy, WM remains incurable. As such, novel therapeutic agents are needed for the treatment of WM.
Experimental design: In this multicenter study, 27 patients with WM received up to eight cycles of bortezomib at 1.3 mg/m(2) on days 1, 4, 8, and 11. All but one patient had relapsed/or refractory disease.
Results: Following therapy, median serum IgM levels declined from 4,660 to 2,092 mg/dL (P < 0.0001). The overall response rate was 85%, with 10 and 13 patients achieving minor and major responses, respectively. Responses were prompt and occurred at median of 1.4 months. The median time to progression for all responding patients was 7.9 (range, 3-21.4+) months. The most common grade III/IV toxicities occurring in > or =5% of patients were sensory neuropathies (22.2%), leukopenia (18.5%), neutropenia (14.8%), dizziness (11.1%), and thrombocytopenia (7.4%). Sensory neuropathies resolved or improved in nearly all patients following cessation of therapy.
Conclusions: The results of these studies show that bortezomib is an active agent in relapsed and refractory WM.