Multiple myeloma maintenance therapy: a review of the pharmacologic treatment.

Over the last decade, numerous drug therapies have emerged for the treatment of multiple myeloma including immunomodulating agents namely thalidomide, lenalidomide, and pomalidomide and proteasome inhibitors namely bortezomib and carfilzomib. These agents have transformed the treatment of multiple myeloma and the role of high-dose chemotherapy followed by stem cell transplantation in the treatment of the disease. There are now studies that evaluate the use of drug therapy as maintenance following autologous stem cell transplantation; these studies have shown improvements in surrogate endpoints such as progression-free survival. Studies that have evaluated thalidomide or lenalidomide maintenance therapy have demonstrated an overall survival (OS) benefit in individuals with multiple myeloma who received high-dose chemotherapy followed by stem cell transplantation. A meta-analysis of thalidomide maintenance therapy did show a possible late survival benefit. The use of dexamethasone, thalidomide, lenalidomide, or combination bortezomib with thalidomide in patients who did not undergo transplantation demonstrated progression-free survival benefit; although there was no OS advantage for these agents in this population. There are a number of important considerations when selecting a drug therapy strategy for maintenance therapy which includes practical considerations such as route of administration and frequency of administration. Additionally, patient-specific elements such as potential toxicities, end-organ function, quality of life, cytogenetics, and previous treatment should be considered. Additional studies are needed to elicit the timing for initiation and duration of maintenance therapy, determine the role of cytogenetics, further characterize possible resistance patterns, and determine the combinations necessary to achieve an optimal increase in OS. Until more data are available, the risks and benefits should be evaluated on a patient-specific basis when deciding to initiate maintenance therapy or observation.