Measurable residual disease recurrence as early warning of relapse in acute myeloid leukemia.

The aim of this study was to investigate the clinical features and outcomes of measurable residual disease recurrence (MRD-R) by multiparameter flow cytometry in acute myeloid leukemia. We retrospectively analyzed clinical characteristics, residual disease status and outcomes of 767 patients with newly diagnosed acute myeloid leukemia who achieved complete remission within two cycles of induction at our center. Overall, 171 (22.3%) patients experienced MRD-R during follow-up. Patients with MRD-R had inferior outcomes compared to those without MRD-R, with 3-year cumulative incidence of morphological relapse (CIR), relapse-free survival (RFS) and overall survival (OS) being 63.6% vs. 30.6% (P<0.001), 13.9% vs. 67.2% (P<0.001) and 39.0% vs. 79.2% (P<0.001), respectively. The outcomes for patients in the groups with minute MRD-R (<0.1%) or overt MRD-R (≥0.1%) were comparable, with 3-year CIR, RFS and OS of 65.2% vs. 68.2% (P=0.76), 28.9% vs. 27.5% (P=0.85), and 44.8% vs. 38.9% (P=0.39), respectively. Early intervention at the time of MRD-R postponed morphological relapse, extending the median interval from MRD-R to morphological relapse to 4.2 months vs. 1.7 months without intervention (P=0.033). Considering these findings together, MRD-R indicated a higher incidence of relapse and poorer outcomes and could serve as an early warning event for relapse in clinical practice. Early intervention could delay relapse, thereby creating a time window for transplantation.