Forcing Ahead: Second-Line Treatment Options for Lenalidomide-Refractory Multiple Myeloma.

The therapeutic landscape for multiple myeloma has gradually expanded in recent decades, leading to unprecedented deep and sustained responses as well as remarkable improvements in patient survival. Nonetheless, changes in treatment algorithms have raised new demands for patients with relapsed/refractory disease, as prior exposure and refractoriness to prior therapies impact the choice of subsequent treatments. In particular, refractoriness to lenalidomide-an established backbone of treatment in both front-line and maintenance settings and a key component of many approved regimens used in relapsed disease-is associated with suboptimal clinical outcomes. Therefore, identifying the most appropriate management in lenalidomide-refractory patients, and even more so in patients who are refractory to more than one agent, is critical. At present, treatment options for this growing subgroup of patients are still limited; however, recent data from clinical research are promising. Herein, we summarized the currently available treatment options and discuss future directions based on the latest results from ongoing clinical trials.