Hyperleukocytosis predicts inferior clinical outcome in pediatric acute myeloid leukemia

Hyperleukocytosis (HL) is a laboratory abnormality commonly presented in patients with acute myeloid leukemia (AML). However, large cohort studies on the clinical significance of HL in pediatric AML are paucity. Moreover, the effect of stem cell transplantation in HL patients remains unknown.

The clinical profiles of 885 pediatric patients with AML were downloaded from the TARGET dataset. HL was defined as an initial peripheral WBC count of ≥ 100 ×10⁹/L. We analyzed the prevalence, clinical profile and prognosis of HL in these patients.

The frequency of HL among all the pediatric AML was 22.6%. FMS-like tyrosine kinase 3/internal tandem duplication (FLT3/ITD) mutation and gene fusion of NUP98/NSD1 occurred with higher incidence in HL patients. Overall, HL was associated with a low induction complete remission rate, and high risk of induction death. Moreover, HL predicted a significantly inferior 5-year event-free survival (EFS) (P < 0.001) and a trend of inferior 5-year overall survival (OS) (P = 0.059). However, compared with chemotherapy, stem cell transplantation had no significant effect on the survival of HL patients in terms of 5-year leukemia-free survival (P = 0.449) or OS (P = 0.447). Multivariate analysis revealed that HL was an independent prognosis factor for EFS (Hazard ratio:1.352, P = 0.013) but not for OS (Hazard ratio:1.225, P = 0.170) in pediatric AML.

HL might predict inferior clinical outcome in pediatric AML. SCT is an effective therapy for AML, but it may have no better effect on the survival of patients with HL, compared to chemotherapy.