Prognostic Significance of CD20 Expression in Children with Philadelphia Chromosome-Negative B-Cell Precursor Acute Lymphoblastic Leukemia

Introduction: The prognostic significance of CD20 in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL) remains unclear. Therefore, in this study, we evaluated the prognostic value of CD20 expression in leukemia blasts in pediatric BCP-ALL at our institute. Methods: Between 2005 and 2017, 796 children with newly diagnosed Philadelphia-negative BCP-ALL were enrolled consecutively; clinical characteristics and treatment outcomes were analyzed and compared between CD20-positive and CD20-negative groups. Results: CD20 positivity was observed in 22.7% of enrolled patients. The analysis of overall and event-free survival showed that white blood cell count >= 50 x 10(9)/L, no ETV6-RUNX1, day 33 minimal residual disease (MRD) >= 0.1%, and week 12 MRD >= 0.01% were independent risk factors. Meanwhile, in the CD20-positive group, week 12 MRD >= 0.01% was the only factor associated with long-term survival. Moreover, subgroup analysis revealed that in patients with extramedullary involvement (p = 0.047), MRD >= 0.1% on day 33 (p = 0.032), or MRD >= 0.01% at week 12 (p = 0.004), CD20 expression led to a poorer outcome compared to those without CD20 expression. Conclusions: Pediatric BCP-ALL with CD20 expression had unique clinicopathological characteristics, and MRD remained the major prognostic factor. CD20 expression had no prognostic value in pediatric BCP-ALL.