Minimal residual disease (MRD) detected at the end of induction therapy is associated with adverse outcomes in both adult and pediatric patients with acute leukemia. However, the assessment of MRD and the clinical significance of low levels of residual disease in the Brazilian context remain unclear.

We conducted a prospective, real-world analysis using high-sensitivity flow cytometry MRD in 60 adults and 67 children with acute leukemia. The aim was to evaluate the kinetics of disease elimination, the bone marrow microenvironment, and correlate these factors with patient outcomes.

Patients with B-cell and T-cell acute lymphoblastic leukemia (B-cell and T-cell ALL) in morphologic complete remission who had MRD analysis at day 15 (d15), day 33 (d33), week 12 post-induction therapy, pre-hematopoietic stem cell transplantation (HSCT), and post-transplantation were enrolled in the study. Patients were divided into two groups based on their MRD test results at d15: the MRD-positive group (MRD+) and the MRD-negative group (MRD-). They were followed at days 30, 60, 90, and 360 after transplantation, depending on survival rates. An 8-color or 10-color flow cytometry tube was used to observe the recovery of B cells and other cells in the bone marrow microenvironment after HSCT.

The study included 60 adult patients (33 MRD- and 27 MRD+) and 67 children (21 MRD+ and 46 MRD-). The overall survival rate was 76.0%, with 50% in the adult cohort and 85.0% in the pediatric cohort. When controlled for d15 MRD status, the survival rate was 97.6% for MRD-negative patients and 78.4% for MRD-positive patients. In the adult cohort, there was a significant difference in outcomes between MRD+ and MRD- patients at the end of induction (55.0% versus 95.0%, p < 0.001). However, in the pediatric cohort, there was no significant difference between MRD+ and MRD- patients at d15 (OS 86.5% versus 98.5%).

MRD status, age, and type of therapy should be considered when developing a prognostic approach for patients with acute leukemia.