The role of high-dose melphalan and autologous stem cell transplant in the rapidly evolving era of modern multiple myeloma therapy.

The advent of the immunomodulatory drugs thalido-mide, lenalidomide, and pomalidomide; the proteasome inhib-itors bortezomib, carfilzomib, and ixazomib; the histone deacet-ylase inhibitor panobinostat; and the monoclonal antibodies elotuzumab and daratumumab has led to dramatic improvements in outcomes for patients with multiple myeloma. Along with progress in nontransplant therapy have come questions regarding the continued role of high-dose melphalan (HDM) supported by autologous stem cell transplant (ASCT) in the treatment of multiple myeloma. Emerging evidence from phase 3 studies demonstrates that consolidation therapy with HDM/ASCT further improves depth of response and progression-free survival in the context of modern therapy for multiple myeloma. Moreover, unprecedented survival data from ongoing phase 3 studies of patients treated with modern myeloma therapy followed by HDM/ASCT in first-line or second-line therapy reaffirm single and tandem HDM/ASCT as important standards of care for eligible patients. Herein, we review the evolving role of HDM/ASCT for the treatment of patients with newly diagnosed or relapsed multiple myeloma.