Consolidation and Maintenance Therapies for Newly Diagnosed Multiple Myeloma in the Era of Novel Agents

Advances in therapy in multiple myeloma have resulted in significant improvements in patient outcomes; however, relapse remains problematic. Strategies to improve outcomes following autologous stem cell transplantation (ASCT) include consolidation to intensify therapy and improve depth of response and maintenance therapy to achieve long-term disease control. Immunomodulatory drugs (IMiDs), including thalidomide and lenalidomide, are appealing as maintenance therapy given their oral administration; however, the cumulative toxicities of thalidomide have limited its efficacy in maintenance therapy. Maintenance lenalidomide is better tolerated, and multiple studies have demonstrated an improvement in progression-free survival (PFS), but its impact on overall survival (OS) remains controversial. Additional concerns regarding the risk of second primary malignancies and significant cost of long-term lenalidomide therapy have also been raised. Proteasome inhibitors, particularly, bortezomib have also been incorporated in consolidation and maintenance regimens alone or in combination with an IMiD. Preliminary studies have suggested bortezomib maintenance may benefit patients with adverse cytogenetics, including t(4;14) and deletion 17p. Determination of the optimal consolidation and maintenance regimen and duration of therapy post-transplantation is a focus of several ongoing randomized studies.