Minimal residual disease in multiple myeloma: the movement towards response-adapted therapy

In recent years, minimal residual disease (MRD) testing has emerged as a powerful prognostic tool in multiple myeloma. Multiple meta-analyses have demonstrated that achieving MRD negativity is associated with significantly improved progression-free survival (PFS), leading to its acceptance as a surrogate endpoint in clinical trials to support accelerated drug approval. Looking forward, MRD status is poised to be incorporated into treatment decision-making; to guide escalation and de-escalation of therapy with the aims of improved progression free survival with limited treatment toxicity. In this review article, we provide an overview of the current modalities available for MRD testing, including bone marrow, peripheral blood, and imaging-based techniques. We examine the prognostic significance of MRD status, with a focus on the impact of sustained MRD negativity, outcomes with MRD resurgence, and the depth of MRD negativity on progression free survival. Finally, we discuss the rapidly evolving landscape of MRD-adapted clinical trials and how these studies are informing the development of response-adapted treatment strategies.