Prognostic implications of CD123 in pediatric B-cell acute lymphoblastic leukemia: a single-center retrospective analysis.

Acute lymphoblastic leukemia (ALL) is the most common pediatric hematologic malignancy, with the majority of cases being of B-cell origin. While many patients respond favorably to therapy, a subset experiences early relapse or poor outcomes, underscoring the critical need for reliable prognostic biomarkers. This study investigated the significance of CD123 expression in diagnosing the disease, evaluating therapeutic efficacy, and predicting prognosis in pediatric B-cell ALL (B-ALL). This retrospective study included 305 pediatric patients with B-ALL admitted to our hematology department from January 2016 to December 2021. All patients were treated following the CCCG-ALL-2015 protocol. Based on flow cytometric evaluation, patients with ≥20% or <20% CD123-expressing blasts were stratified into CD123-positive (CD123+) and CD123-negative (CD123-) groups, respectively. CD123 was expressed on the leukemic blasts of 60.3% of patients, exhibiting a strong positive correlation with CD34 expression (P < 0.001). CD123 positivity was substantially associated with specific genetic abnormalities. Specifically, the frequencies of the ETV6::RUNX1 and TCF3::PBX1 fusion genes were significantly lower in the CD123+ group than in the CD123- group. The 5-year event-free survival (EFS) rate was significantly higher in the CD123+ group than in the CD123- group (P = 0.027). This favorable prognostic impact was particularly pronounced in patients exhibiting minimal residual disease (MRD) positivity on day 19 (P = 0.006). Furthermore, combining CD123 status with day 19 MRD enabled more accurate identification of patients with a poor prognosis. CD123 positivity on leukemic blasts correlates with distinct genetic profiles and favorable clinical outcomes in pediatric B-ALL. Ultimately, integrating CD123 status with early treatment response facilitates accurate risk stratification and guides personalized therapeutic strategies.