Fig 4.
Trajectories of treatment in smoldering multiple myeloma (SMM). Theoretically, treatment response in SMM can branch into seven different scenarios. (1) A group may show no response to treatment and progress, as seen in treatment with interleukin-1 receptor antagonist52 or bisphosphonates.49 (2) Treatment can slow disease progression without meeting criteria for partial response (PR). (3) Treatment can achieve PR followed by slow disease progression (as shown in 3) or stable disease (not shown). As an example, single-agent thalidomide was able to achieve PR in 25%43 and 47.5% of patients50 in two different trials. (4) Some patients who achieved PR or complete response (CR) may undergo selection of fitter clones and later have an accelerated progression. This was an observed phenomenon as shown by a shorter time to progression in the PR group treated with thalidomide.50 (5, 6, 7) Treatments can lead to CR, as seen in 14% of patients with SMM treated with lenalidomide and dexamethasone34 or up to 100% when treated with a three-drug combination.48 Long-term follow-ups are required to monitor the consequence after CR, which may be followed by relapse with slow progression (5), stable disease with a disease burden below the level of detection (shown as minimal residual disease [MRD]; 6), or cure (7). MM, multiple myeloma; Rx, treatment.