Bortezomib and dexamethasone for Japanese patients with relapsed and refractory multiple myeloma: a single center experience.

Bortezomib is a novel proteasome inhibitor, which has shown high antimyeloma activity. APEX trial, phase III randomized study for relapsed or refractory myeloma established efficacy and feasibility of bortezomib. In our study, we retrospectively investigated 60 Japanese patients with relapsed or refractory multiple myeloma (MM) who underwent bortezomib and dexamethasone (BD) therapy in our institution. Overall response rate was 75%, including 7 cases (11.7%) of complete response and 13 cases (21.7%) of very good partial response. Stable disease and progressive disease were observed in 15 patients (25%). Major ≥ grade 3 adverse events were hematological toxicities and grade 3 non-hematological toxicities included appetite loss, diarrhea and peripheral neuropathy. BD therapy was well tolerated, and produced significant response in relapsed or refractory MM patients. Recently, many worldwide trials including bortezomib or other new agents are ongoing to evaluate its efficacy not only as a therapy for relapsed or refractory disease but also as a frontline therapy. Further investigations are required to define how to use new antimyeloma agents for Japanese MM patients.