The treatment of multiple myeloma has evolved from being time-limited to a continuous strategy, made possible with the development of well tolerated drugs amenable to prolonged use. Continuous maintenance therapy improves progression-free survival and overall survival for patients either eligible or ineligible for transplantation. 1 Paul Singh P Kumar SK LaPlant BR et al. Lenalidomide maintenance therapy in multiple myeloma: a meta-analysis of randomized trials.

Blood. 2013; 122 (407): 407

, 2 McCarthy PL Holstein SA Petrucci MT et al. Lenalidomide maintenance after autologous stem-cell transplantation in newly diagnosed multiple myeloma: a meta-analysis.

J Clin Oncol. 2017; 35: 3279-3289

The bulk of evidence for lenalidomide maintenance comes from trials in which no monitoring of disease was done beyond the detection of paraprotein in serum or urine, and in which presumably, very few patients were negative for minimal or measurable residual disease (MRD).