Noelle Frey, MD, from the University of Pennsylvania, Philadelphia, PA, highlights the importance of minimal residual disease (MRD) assessment in predicting the long-term effects of therapy in acute lymphoblastic leukemia (ALL) patients, and the steps that should be followed if a patient is MRD-positive after the administration of CAR T-cell therapy or other forms of treatment. This interview was recorded at the 2018 European School of Hematology (ESH) Clinical Updates on Acute Leukemias, held in Budapest, Hungary.