Hyperleukocytosis and outcomes in pediatric B-cell acute lymphoblastic leukemia: A report from the REDIAL Consortium

A study analyzed 1,826 pediatric acute lymphoblastic leukemia (ALL) patients from multiple healthcare institutions to determine whether hyperleukocytosis (white blood cell count >100,000/μL) independently predicts treatment outcomes. Hyperleukocytosis occurred in 211 patients (12%), with 121 having B-ALL. In B-ALL patients, five-year event-free survival was 65% compared to 89% in non-hyperleukocytosis patients, and overall survival was 78% versus 93%. After adjustment for age, cytogenetic risk, and other factors, hyperleukocytosis remained an independent predictor of worse prognosis. A continuous dose-response relationship was observed between white blood cell count and treatment outcomes. Despite intensive therapy, hyperleukocytosis identifies an aggressive B-ALL phenotype with persistently inferior outcomes, suggesting the need for novel therapeutic approaches.