[Clinical Characteristics and Prognostic Analysis of Childhood Acute Lymphoblastic Leukemia with Positive E2A-PBX1 Fusion Gene]

Abstract

Objective: To explore the clinical characteristics, therapeutic responses and prognostic features of E2A-PBX1 fusion gene for childhood acute lymphoblastic leukemia (ALL).

Methods: A total of 837 pediatric patients with ALL who were initially diagnosed in our hospital from July 2010 to November 2017 were retrospectively analyzed, 48 children with positive E2A-PBX1 fusion gene were detected by the real-time quantitative PCR techniques and their data were retrospectively collected for analysis.

Results: Among 48 cases with positive E2A-PBX1 fusion gene, there were 26 males and 22 females, with onset ages ranging from 9 months to 13 years old. There were 2 cases (4.2%) in the low-risk group, 32 cases (66.7%) in the intermediate-risk group, and 14 cases (29.1%) in the high-risk group at initial diagnosis. The white blood cell (WBC) counts of 25 cases (53.2%) at initial diagnosis were <50×10⁹/L, 11 cases (23.4%) were (50-100)×10⁹/L, and 11 cases (23.4%) ≥100×10⁹/L. The main immunophenotype was common-B ALL (44 cases, 91.7%). Other leukemia fusion genes such as BCR-ABL1, MLL-AF4, and TEL-AML1 were not observed in this cohort of patients. All patients received the treatment of NPCLC-ALL2008 protocol, and 5 cases (10.4%) occurred poor prednisone response. All the 48 cases achieved complete remission (CR) after the induction treatments. The last follow-up date was April 30, 2023. A total of 5 children relapsed, including 1 case with intermediate risk and 4 cases with high risk. The recurrence rate in the high-risk group was significantly higher than that in the intermediate- and low-risk groups (both P < 0.05). Most relapsed children had elevated WBC counts at initial diagnosis. Among them, WBC counts ≥100×10⁹/L was observed in 4 cases. The recurrence rate among children with WBC counts ≥100×10⁹/L was significantly higher than that with WBC counts <100×10⁹/L (P < 0.01). Four deaths occurred in this cohort, of which 3 died of leukemia recurrence. The 10-year event-free survival rate and 10-year overall survival rate of the 48 children with positive E2A-PBX1 fusion gene were 87.5%±4.8% and 91.7%±4.0%, respectively.

Conclusion: In ALL children with positive E2A-PBX1 fusion gene, those with elevated WBC counts and high risk stratification at initial diagnosis are more likely to experience recurrence. Recurrence is the main cause of death in this group. It is suggested that such kind of children receive more intensive chemotherapy or undergo hematopoietic stem cell transplantation as early as possible to further improve prognosis.

Keywords: E2A-PBX1 fusion gene; acute lymphoblastic leukemia; relapse; prognosis.