[HER2 Expression in Childhood ETV6/RUNX1⁺ Acute Lymphoblastic Leukemia and Its Correlation with Clinical Features]

To explore the HER22 expression in children with ETV6/RUNX1 (E/R)-positive acute lymphoblastic leukemia(ALL) and to investigate the relationship between the HER2 expression and clinical features.

Thirty-seven newly diagnosed E/R-positive ALL children and 6 controls (4 cases of ITP and 2 healthy children) were selected in Institute of hematology and blood disease hospital. The 37 patients were divided into standard risk (SR), intermediate risk(IR), high risk(HR) groups according to risk stratification; and they were divided into relapse and non-relapse groups according to follow-up result. The CD10⁺CD19⁺ cells were sorted by flow cytometry. The mRNA was extracted from these cells. Real-time fluorescent quantitative PCR was used to detect the expression level of HER2.

Among the 37 cases, 51.35% (n=19) were boys and 48.65% (n=18) were girls and their median age was 4.72 (1.72-11.99) years old. Among the 6 controls, 50% (n=3) were boys and 50% (n=3) were girls and the median age was 5.24 (1.53-13.17) years old. The expression level of HER2 in E/R-positive ALL patients were lower than that in controls (P<0.05). Although the difference of HER2 expression level between the 2 groups failed to achieve statistical significance, the expression level of HER2 in relapse patients were significantly lower than that in non-relapse patients, and the HER2 expression in HR group patients were lower than that in SR and IR groups. In addition, there was no significant correlation between the expression level of HER2 and the sex, age, initial white blood cell count, blast cell percentage and the level of LDH (P>0.05).

The expression level of HER2 in E/R⁺ ALL patients is lower than that in controls, and in relapse group lower than that in non-relapse patient. Thus, HER2 may play important roles in the pathogenesis and relapse mechanism of pediatric E/R-positive ALL patients.