Relapsed multiple myeloma.

Advances in treatment options for patients with multiple myeloma have made a significant impact on the overall survival of patients and have helped achieve levels of response and duration of remission previously not achievable with standard chemotherapy-based approaches. These improvements are due, in large part, to the development of the novel agents thalidomide, bortezomib, and lenalidomide, each of which has substantial single-agent activity. In addition, a large number of second-generation agents are also in clinical development, such that the repertoire of available treatment options continues to expand. To better interpret clinical trials performed in the relapsed setting, it is important that definitions of relapse categories are used to help better pinpoint the specific benefit for a given therapy, especially in the combination therapy setting as it aids in determining if ongoing work should be continued or abandoned for a given new agent. Insights from preclinical modeling and in vitro work have identified several new combinations, new targets and second- or third-generation versions of existing targets that hold great promise in the setting of relapsed myeloma. Combinations of thalidomide, bortezomib, and lenalidomide with conventional agents or among each other have resulted in enhanced response rates and efficacy. Clinical trials of agents such as carfilzomib, pomalidomide, vorinostat, panobinostat, and elotuzomab are just a few of the many exciting new compounds that are being tested in phase 1 and phase 2 clinical trials for relapsed patients. Further clinical and translational testing are critical to better understanding how best to combine these new agents, as well as identifying patient populations that may best benefit from treatment with these developing new agents.