Multiple myeloma: from front-line to relapsed therapies.

Recent developments in the treatment of multiple myeloma (MM) have led to improvements in response rates and to increased survival. A major advance in the last decade has been the introduction of the novel agents thalidomide, bortezomib, and lenalidomide as part of front-line treatment in both the transplant and nontransplant settings. However, disease relapse is inevitable for the majority of patients and myeloma typically recurs more aggressively with each relapse, eventually leading to the development of treatment-refractory disease. Several phase II and III trials have demonstrated the efficacy of recently approved agents in the setting of relapsed and relapsed and refractory MM, including pomalidomide and carfilzomib. Ixazomib, an oral proteasome inhibitor, and multiple other novel classes of agents are being investigated. These include monoclonal antibodies and histone deacetylase inhibitors, which may further add to the therapeutic armamentarium for this malignancy. Therefore, in a disease characterized by multiple relapses, the optimal sequencing of the different effective options is an important consideration in attempting to prolong survival.