Meeting report: Advances in minimal residual disease testing in multiple myeloma 2018

This report summarizes the 5th annual symposium on minimal residual disease (MRD) testing in multiple myeloma gathered experts from academia, industry and the FDA in New York City on 14 September 2018. Three recommendations were made: (a) MRD testing should be performed in patients who achieve a very good partial response (VGPR) in addition to complete response (CR); (b) MRD negativity at one tumor cell in 1 000 000 bone marrow cells (10⁻⁶) should be considered as a response category alongside the current definition of MRD negativity at 10⁻⁵; and (c) clinical trials reports should specify the sensitivity of MRD testing as well as the applied threshold for MRD negativity (ie, 10⁻⁵ or 10⁻⁶), and if possible report outcome data for both MRD thresholds. Overall, as discussed at the meeting, there is already solid evidence that bone marrow based MRD assessment is one of the strongest prognostic factors in multiple myeloma, and deeper responses correlate with increasingly favorable outcomes. Indeed, achieving MRD negativity appears to be more important than what treatment was used to get there. Going forward, there is a need for clinical trials focusing on MRD-directed therapy to determine the role of MRD testing in everyday clinical decision-making. Standardization of MRD testing and harmonization across centers will make it easier to learn from common experiences. Ongoing efforts are anticipated to establish MRD status as a regulatory endpoint for accelerated drug approval in multiple myeloma in the near future.