Bortezomib plus dexamethasone as induction treatment prior to autologous stem cell transplantation in patients with newly diagnosed multiple myeloma: results of an IFM phase II study

Background and objectives. Induction regimens prior to autologous stem cell transplantation (ASCT) in newly diagnosed multiple myeloma patients usually result in complete remission (CR) rates of <10%. The use of novel agents may increase the CR rate before ASCT, which may improve post-transplantation response and survival. Design and methods. This was a phase II, open-label trial of bortezomib (1.3 mg/m(2), days 1, 4, 8, 11) and dexamethasone (40 mg, days 1-4 and 9-12 for cycles 1-2, days 1-4 for cycles 3-4) administered for four 21-day cycles as induction therapy in chemotherapy-naive myeloma patients. Results. Of 52 recruited patients, 48 were eligible for the study. The overall response rate was 66% including 21% CR and 10% very good partial remission (>90% reduction of the M-component). Four patients had a minimal response, six had stable disease and five had progression. One patient died after salvage therapy with VAD. The most common side effects were gastrointestinal symptoms, peripheral neuropathy, and fatigue. These were usually mild. Peripheral neuropathy was observed in 15 cases but was grade 2-3 in only seven cases (14%). There was no deep vein thrombosis and no hematologic toxicity greater than grade 2. Grade 3 infections were recorded in five patients including three who had herpes zoster infections. Stem cell collection was programmed in 44 cases and all patients had sufficient CD34(+) cells to perform one ASCT (> 2x10(6)/kg). Interpretation and conclusion. This regimen of bortezomib plus dexamethasone appears effective and well tolerated in newly diagnosed myeloma patients.