Post-induction measurable residual disease evaluation in pediatric B-acute lymphoblastic leukemia and its related factors; a prospective observational study based on flow cytometry

Introduction: B-acute lymphoblastic leukemia (B-ALL) is the most common pediatric malignancy. Despite significant advancements in treatment protocols, relapse remains a major challenge. Measurable residual disease (MRD), defined as the presence of leukemic cells below the detection threshold of conventional microscopy, has emerged as a robust prognostic marker. Objectives: This study investigates post-induction MRD levels in pediatric patients with B-ALL and examines factors influencing MRD positivity. Patients and Methods: This prospective observational study employed multi-parametric flow cytometry (MFC) to evaluate MRD levels in 38 pediatric B-ALL patients following induction therapy referred to Nanakali hemato-oncology center in Erbil, Iraq, between June 2023 and June 2024. The cohort included children aged 1–15 years diagnosed with B-ALL. Bone marrow (BM) samples were collected at the end of induction therapy, since MRD was quantified using a flow cytometry protocol. Clinicopathological data were analyzed to identify factors associated with MRD status. Results: Out of 38 B-ALL patients, 11 (28.9%) were MRD-positive and 27 (71.1%) were MRD-negative. In the unadjusted analysis, a white blood cell (WBC) count exceeding 50×109 /L was strongly associated with MRD positivity, with an odds ratio (OR) of 6.90, indicating a significantly higher likelihood of MRD detection. In contrast, hemoglobin (Hb) levels demonstrated a protective effect; for every 1 g/dL increase in Hb, the odds of MRD positivity decreased by 43%, corresponding to an OR of 0.57. Additionally, BM blast percentages on day 8 and post-induction (day 35) were significantly correlated with MRD positivity, with ORs of 12.57 and 5.12, respectively. However, age, gender, baseline symptoms, lymphadenopathy, organomegaly, symptom duration, and cytogenetic abnormalities, platelet count, peripheral blood blasts, treatment type, and lactate dehydrogenase (LDH) levels showed no statistically significant correlation with MRD status. Conclusion: Our study findings highlight the importance of WBC count, BM blast percentages, and Hb levels in risk stratification of MRD positivity, suggesting targeted interventions for high-risk patients could improve outcomes.