Acute lymphoblastic leukemia (ALL) is the first pediatric cancer where the assessment of early response to therapy by minimal residual disease (MRD) monitoring has demonstrated its importance to improve risk-based treatment approaches. The most standardized tools to study MRD in ALL are multiparametric flow cytometry and realtime-quantitative polymerase chain reaction amplification-based methods. In recent years, MRD measurement has reached greater levels of sensitivity and standardization through international laboratory networks collaboration.
We herewith describe how to assess and apply the prognostic impact of MRD in treatment decisions, with specific focus on pediatric ALL. We also highlight the role of MRD monitoring in the context of genetically homogeneous subgroups of pediatric ALL. However, some queries remain to be addressed and emerging technologies hold the promise of improving MRD detection in ALL patients.
Emerging technologies, like next generation flow cytometry, droplet digital PCR, and next generation sequencing appear to be important methods for assessing MRD in pediatric ALL. These more specific and/or sensitive MRD monitoring methods may help to predict relapse with greater accuracy, and are currently being used in clinical trials to improve pediatric ALL outcome by optimizing patient stratification and earlier MRD-based interventional therapy.