Second autologous transplant as salvage therapy in multiple myeloma.

High-dose chemotherapy followed by autologous haematopoetic stem cell transplantation (ASCT) is a standard frontline therapy for multiple myeloma (MM). Unfortunately, there are no randomized clinical studies examining the role of a second ASCT in patients who relapse after the initial autotransplant. Analysing all available retrospective studies, it seems that salvage ASCT can safely be performed in most patients with an overall treatment-related mortality rate <5%. Approximately 65% of patients will achieve an objective response and progression-free and overall survival will be around 12 months and 32 months, respectively. Retrospective data suggest that patients with a progression-free survival of ≥18 months after initial ASCT are most likely to benefit from a salvage autotransplant. However, patients with a <12-month duration of response after initial ASCT should not be considered for a second autograft in the relapsed setting because this group will probably only experience ASCT-related toxicity without any clinical benefit. Quality of response after initial ASCT and number of therapies preceding salvage ASCT may also have a predictive value. Importantly, these findings need to be verified by randomized clinical trials in order to firmly integrate salvage ASCT into a global therapeutic concept for myeloma patients including optimized induction, consolidation, and maintenance approaches.