According to a review published in Biology of Blood and Marrow Transplantation, salvage second autologous hematopoietic cell transplantation (SAT) appears to be underutilized in patients with relapsed multiple myeloma (MM), and studies from the last decade are largely heterogeneous with a variety of conditioning regimens, various intervals between transplants, and inconsistent post-transplantation maintenance therapies.

The authors assessed recent studies and clinical trials on SAT for relapsed MM in light of recent developments in the disease treatment. One critical issue is that the specific patient population fit for SAT is still controversial. The authors highlighted that ideally any patient with at least 18 months of progression-free survival following the first autologous stem cell transplantation is a potential candidate for SAT and urge that SAT should not be delayed by awaiting multiple lines of therapy to fail following an initial relapse.

The role of SAT following reinduction appears to be understudied and often unreported. For example, several meta-analyses have been conducted that compare newer regimens for relapsed MM and the combination of daratumumab, lenalidomide, and dexamethasone appears to be superior to other regimens. However, the outcomes for SAT were not assessed in any of these analyses. Furthermore, most of the literature on SAT is composed of single institution studies with varying practices, and the authors identified only 1 randomized study that evaluated the role of SAT compared with a non-transplant approach.

Despite the promising results of CAR-T cell therapy studies, the authors noted that long-term follow ups have not been conducted, and with relapse in MM generally being “the rule not the exception”, they warn that caution should be taken with these patients.

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Lastly, the investigators emphasized the need for novel condition regimens and a standardized post-transplantation maintenance approach and suggested that more randomized clinical trials are needed to compare SAT to non-transplant approaches in patients with relapsed/refractory MM.

Reference

1.     Hagen PA, Stiff P. The role of salvage second autologous hematopoietic cell transplantation in relapsed multiple myeloma [published online December 8, 2018]. Biol Blood Marrow Transplant. doi: 10.1016/j.bbmt.2018.12.002