Impact of pretransplant therapy and depth of disease response before autologous transplantation for multiple myeloma.

Patients with multiple myeloma (MM) who are eligible for autologous stem cell transplantation (ASCT) typically receive a finite period of initial therapy before ASCT. It is not clear if patients with suboptimal (less than a partial) response to initial therapy benefit from additional alternative therapy with intent to maximize pretransplant response. We identified 539 patients with MM who had an ASCT after having achieved less than a partial response (PR) to first-line induction chemotherapy between 1995 and 2010. These patients were then divided into 2 groups: those who received additional salvage chemotherapy before ASCT (n = 324) and those who had no additional salvage chemotherapy immediately before ASCT (n = 215). Additional pretransplant chemotherapy resulted in deepening responses in 68% (complete response in 8% and PR in 60%). On multivariate analysis there was no impact of pretransplant salvage chemotherapy on treatment-related mortality, risk for relapse, progression-free survival, or overall survival. In conclusion, for patients achieving less than a PR to initial induction therapy, including with novel agent combinations, additional pre-ASCT salvage chemotherapy improved the depth of response and pre-ASCT disease status but was not associated with survival benefit.