Clinical features and prognostic implications of ecotropic viral integration site 1 (EVI1) in childhood acute lymphoblastic leukemia.

In contrast to the extensive knowledge on EVI1 in myeloid malignancies, few data are available on the EVI1 transcript in pediatric ALL. The purpose of this study was to examine the clinical and biological significance of EVI1 and validate its prognostic significance in pediatric patients with ALL. Here, we examined the clinical and biological significance of EVI1 expression, as measured by real-time polymerase chain reaction (PCR) in 837 children with newly diagnosed ALL treated on the National Protocol of Childhood Leukemia in China (NPCLC)-ALL-2008 protocol, and aimed to explore their prognostic significance in pediatric ALL patients. The EVI1 expression was detected in 27 of 837 (3.2%) patients. No statistically significant differences in prednisone response, complete remission (CR) rates and relapse rates were found between EVI1 overexpression (EVI1⁺) group and EVI1^- group. Moreover, we found no significant difference in event-free survival (EFS) and overall survival (OS) between these two groups, also multivariate analysis did not identify EVI1⁺ as an independent prognostic factor. In the subgroup analysis, there was no difference in clinical outcome between EVI1⁺ and EVI1^- patients in standard‑risk (SR), intermediate-risk (IR) and high-risk (HR) groups. In the minimal residual disease (MRD)<10^-4 group, EVI1⁺ patients have significantly lower EFS and OS rates compared to EVI1^- patients. Further large‑scale and well‑designed prospective studies are required to confirm the results in the future.