Efficacy and safety of bortezomib-containing induction chemotherapy for autologous stem cell transplantation-eligible Japanese multiple myeloma patients — A phase 2 multicenter trial —

A phase II multicenter trial was conducted to analyze the efficacy and safety of a bortezomib-containing regimen for induction prior to autologous stem cell transplantation (ASCT) in newly-diagnosed multiple myeloma Japanese patients under the age of 65. The induction regimen consisted of one cycle of vincristine-doxorubicin-dexamethasone followed by 3 cycles of twice-weekly bortezomib-dexamethasone (BD). Responding patients underwent stem cell harvesting and ASCT. The primary endpoint was the post-induction response rate (RR). Forty-one patients were enrolled from September 2009 to December 2012. Post-induction RR was 85.4% including 17.1% CR, 4.9% nCR, and 34.1% VGPR. Three-year progression-free and overall survival were 51.9% and 90.3%, respectively. During induction, grade ≥3 hematologic adverse events (AEs) were frequent, of which infection was the most prevalent: 2 events during VAD and 7 events during BD. A total of 8 patients (19.5%) dropped out during induction due to AEs. Furthermore, 15 patients dropped out prior to ASCT, 10 of whom were due to AEs. Only 26 patients (63.4%) proceeded to ASCT, resulting in a relatively low RR after ASCT (58.5%, including 14.6% CR, 17.1% nCR, and 12.2% VGPR). Clinicians must be wary of possible serious AEs, both during and after BD induction, when applied to Japanese patients.