Measurable residual disease detection in acute leukemia: Technological advances and clinical translation.

Measurable residual disease (MRD) has become a central biomarker in acute leukemia, transitioning from a research tool to an essential component of clinical practice. Advances in multiparameter flow cytometry, quantitative PCR, and error-corrected next-generation sequencing have increased detection sensitivity to as low as one leukemic cell among 105-106 normal cells, far surpassing conventional morphology. Across acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL), MRD negativity is consistently associated with lower relapse risk and superior survival. MRD status informs risk stratification, consideration of allogeneic hematopoietic stem cell transplantation, and post-remission monitoring strategies. In selected clinical contexts, most clearly MRD-positive B-cell ALL, MRD can serve as a trigger for therapeutic intervention, whereas in many AML settings MRD-directed intensification with targeted agents remains investigational and is best pursued within prospective trials. However, MRD implementation remains heterogeneous, and important challenges persist, including assay standardization, distinction between true residual leukemia and clonal hematopoiesis, and definition of optimal monitoring schedules and intervention thresholds. This review summarizes current MRD detection technologies, their prognostic and therapeutic implications in acute leukemia, and future directions for integrating MRD into individualized, biology-driven treatment algorithms.