Quantitative cytoplasmic CD79a expression as a predictor of isolated and combined CNS relapse in pediatric B-cell precursor acute lymphoblastic leukemia

Background : CNS relapse remains a major cause of treatment failure in pediatric B-ALL. Methods: We quantified diagnostic cytoplasmic CD79a (CyCD79a) by percentage positivity and intensity metrics in 331 children with B-ALL and tested associations with early response (day-15 MRD), relapse patterns, and survival. Objective : This study evaluates cytoplasmic CD79a (CyCD79a) expression in one of the largest single-center cohorts of pediatric B-ALL patients and its impact on clinical outcomes, including early therapy response, relapse, and survival. Methods : CyCD79a expression was analyzed by flow cytometry in bone marrow samples from 331 pediatric B-ALL patients at diagnosis. Correlations with clinical parameters, minimal residual disease (MRD) on day 15, relapse patterns, and survival were assessed. Results : Higher CyCD79a metrics were associated with day-15 MRD positivity and increased risk of CNS/combined relapse. A CyCD79a cut-off of 73.5% predicted CNS relapse with AUC 0.856 (95% sensitivity, 82% specificity). High CyCD79a was linked to inferior OS/DFS. Conclusion : CyCD79a is a significant prognostic marker in pediatric B-ALL, serving as a robust indicator of high-risk disease and early chemoresistance. The derived cut-off values provide a practical tool for risk stratification and identifying patients who may benefit from intensified or targeted therapies.