Management of Relapsed and Refractory Multiple Myeloma
Journal of Clinical Outcomes Management. 2016 October;23(10)
References
As part of therapy selection in RRMM, the clinician needs to consider if the patient is a candidate for ASCT. For patients who did not undergo ASCT as part of initial treatment, ASCT can be considered at the time of relapse. Ideally, all patients who could eventually undergo ASCT should have hematopoietic stem cells collected and stored at the time of first induction; however, collection after re-induction chemotherapy has been shown to be feasible [28,29]. ASCT for RRMM appears to be effective, although rigorous randomized comparisons of ASCT versus treatment purely with novel drugs are lacking [30–32]. For patients who did receive ASCT consolidation in the frontline, if a response is sustained for 18 months or greater, existing guidelines suggest that a second ASCT is likely worthwhile [29]. Whether the routine usage of maintenance therapies (low-dose, usually single drugs used to prolong duration of remission once remission is achieved) should change that 18-month cutoff is unclear, however, since maintenance “artificially” makes ASCT appear more effective by prolonging post-ASCT duration of remission. The “is it worth it” discussion is also largely subjective and hinges heavily on the patient’s experience with the first ASCT. In our practice, we often use 3 years as the cutoff for considering repeat ASCT in patients on maintenance therapy, meaning that if a patient underwent ASCT and received maintenance, a remission lasting more than 3 years means we consider ASCT as part of therapy for relapse.
Allogeneic stem cell transplantation (allo-SCT) is a treatment option for RRMM generally reserved for fit patients younger than 65 years [22,33]. The timing of allo-SCT is also controversial, with some reserving it as a last option given a historically high transplant-related mortality and improved progression-free survival but not necessarily overall survival benefit. A recent consensus statement has suggested allo-SCT be considered (preferentially in a clinical trial) for eligible patients with high-risk disease who relapse after primary treatment that included ASCT [29]. With the abundance of new treatment options in RRMM with reasonable toxicity profiles, it is not clear for whom and when allo-SCT is best considered.
Table 1 summarizes some of the considerations discussed for selecting therapy for RRMM.
Which regimen should be used to treat a first relapse?
Entry into a well-designed clinical trial for patients with RRMM should be considered for every patient since there is a lack of evidence to guide the best sequencing of chemotherapies [11]. Beyond that, the choice of therapy is based upon 2 main factors: the disease itself (eg, indolent, asymptomatic biochemical recurrence versus aggressive clinical recurrence with new fractures or extramedullary plasmacytomas), and the patient’s preferences and characteristics, such as age, performance status, comorbidities, and toxicities from prior therapies. In looking for the “best” re-induction regimen, it is tempting to compare the efficacy of regimens across trials, but such efforts are fraught given the significant heterogeneity of the patient populations between trials. As an example, comparing daratumumab + pomalidomide + dexamethasone (DPd) to daratumumab + lenalidomide + dexamethasone (DRd), one may conclude that DRd is superior, given an overall response rate of 88% in DRd versus 58% in DPd. However, the DPd trial included patients who were refractory to lenalidomide and bortezomib, while the DRd study required only treatment with one prior therapy [34,35].
