The response to second-line induction with bortezomib and dexamethasone is predictive of long-term outcomes prior to high-dose chemotherapy with autologous stem cell transplantation for multiple myeloma

Objective We retrospectively investigated the efficacy and predictive factors for the treatment outcomes of bortezomib plus dexamethasone (BD) as second-line induction therapy prior to high-dose chemotherapy sup- ported by autologous stem cell transplantation (HDT/ASCT) in multiple myeloma (MM) patients. Methods Sixty-six transplant eligible MM patients treated by the Kyoto Clinical Hematology Study Group between 2006 and 2011 were investigated. Conventional induction chemotherapy, including vincristine, dox- orubicin and dexamethasone (VAD) and high-dose dexamethasone (HDD), was used as first-line induction therapy in all patients, seven (10.6%) of whom attained a very good partial response (VGPR). Of the 59 pa- tients who did not attain VGPR with VAD or HDD, 33 were given BD as second-line induction therapy prior to HDT/ASCT. Results Patients not treated with BD induction showed an overall response rate (ORR, i.e., better than par- tial response) of 85.3% after induction therapy, while the ORR of patients treated with BD induction im- proved from 42.4% after conventional induction therapy to 84.8% after BD. The overall survival (OS) and progression-free survival (PFS) of patients not treated with BD induction were not significantly influenced by the response to induction therapy. Among the patients treated with BD, failure in attaining VGPR prior to ASCT was associated with a significantly shorter PFS and it also tended to show a shorter OS, while the dis- ease stage and achievement of a complete response after HDT/ASCT had no impact on OS or PFS. Conclusion The achievement of at least VGPR with second-line BD induction therapy is a prerequisite for attaining longer OS and PFS after HDT/ASCT.