The treatment of multiple myeloma has evolved significantly over the past 2 decades due to the use of high-dose chemotherapy and autologous stem cell transplantation, and the subsequent introduction of the immunomodulatory agents (thalidomide and lenalidomide) and the proteasome inhibitor (bortezomib). The median overall survival of multiple myeloma patients has increased significantly with patients younger than age 50 years experiencing a 10-year survival rate of around 40%. However, despite the increased effectiveness of the first-line agents, the majority of patients will eventually relapse and become drug resistant. Promising novel therapies have recently emerged and are being used to treat relapsed and refractory patients. This review ...