Minimal Residual Disease in Multiple Myeloma: Something Old, Something New

SIMPLE SUMMARY: Currently, response rates in multiple myeloma (MM) have increased dramatically, with more than 50% otablef those who respond satisfying complete response criteria. Achieving frequent deep responses has necessarily led to test conceptual advantages for assessing and treating MM patients with only minimal residual disease (MRD). In this review, we present and discuss the clinical relevance, methodology, and challenges for measuring MRD in MM. ABSTRACT: The game-changing outcome effect, due to the generalized use of novel agents in MM, has cre-ated a paradigm shift. Achieving frequent deep responses has placed MM among those neoplasms where the rationale for assessing MRD is fulfilled. However, its implementation in MM has raised specific questions: how might we weight standard measures against deep MRD in the emerging CAR-T setting? Which high sensitivity method to choose? Are current response criteria still useful? In this work, we address lessons learned from the use of MRD in other neoplasms, the steps followed for the harmonization of current methods for comprehensively measuring MRD, and the challenges that new therapies and concepts pose in the MM clinical field.