The introduction of novel molecular targeting agents against multiple myeloma has dramatically and rapidly changed the therapeutic strategies for this incurable hematologic disease. Novel agents such as thalidomide, bortezomib and lenalidomide have significantly improved the response rate, progression-free survival, and overall survival compared with conventional chemotherapies, and made it easy to control the disease for longer periods of time. Initial therapies for newly diagnosed myeloma patients depend on the individual's clinical condition. Induction therapy with novel agents and high-dose chemotherapy followed by autologous stem cell transplantation is a standard therapy for newly diagnosed younger myeloma patients. On the other hand, several combinations of novel agents and other drugs (melphalan, prednisone, dexamethasone, etc.) are widely used as initial therapy for transplantation-ineligible myeloma patients. Although the clinical advantage of maintenance therapy after induction therapy has been reported, it is not recommend in routine practice. Maintenance therapy would be an option for some patients. Despite the significant improvements with the use of novel agents, the majority of patients eventually relapse. A number of treatment options including novel agents, which demonstrated marked clinical effects, are reported in the setting of salvage therapy. The choice of appropriate therapy for relapsed or refractory patients must take the disease status or patient status in consideration. Furthermore, a new generation of novel agents such as pomalidomide, carfilzomib or panobinostat has recently become available for relapsed or refractory myeloma. It is necessary to determine the optimal combination of drugs, administration timing and patients to be treated in future clinical trials.
