Abstract: Background：Children with refractory and relapsed acute lymphoblastic leukemia (ALL) have poor prognosis. It is significant to identify new molecular markers with prognostic value to assist in prognosis assessment. Objective：To explore the expression level of the IDE gene in children with ALL and its correlation with prognosis. Design：Retrospective cohort study. Methods：A total of 77 newly diagnosed ALL patients admitted to Beijing Children's Hospital, Capital Medical University, from January 1st, 2020, to October 31st, 2020, were included in the study as a testing cohort. The expression level of the IDE gene in bone marrow mononuclear cells at diagnosis was analyzed using ROC curve analysis to set the IDE cutoff value, comparing the prognosis of highexpression and lowexpression groups. The validation cohort consisted of ALL patients admitted to Henan Children's Hospital during the same period, and it was used to verify the correlation between the established IDE cutoff grouping criteria and prognosis. Prognostic factors, including clinical biological characteristics and early treatment responses, were also analyzed. Main outcome measures：Eventfree survival (EFS). Results：A total of 77 newly diagnosed ALL patients were included, with 37 in the testing cohort and 40 in the validation cohort. The expression level of the IDE gene at diagnosis was correlated with the prognosis of ALL. Patients with adverse events had significantly higher IDE expression levels at diagnosis than those without adverse events (P<0.001). ROC analysis showed that the IDE gene expression level could predict the prognosis of ALL patients, with an AUC of 0.961 (P<0.001). The cutoff value was set as 0.72 by the ROC curve. In the testing cohort, the highexpression group (IDE≥0.72, n=19) had a significantly worse prognosis than the lowexpression group (IDE<0.72, n=18), with 3year EFS rates of 55.7% and 100%, respectively (P=0.002). In the validation cohort, the highexpression group (n=26) and lowexpression group (n=14) had 3year EFS rates of 64.3% and 96.2% (P=0.009), which was statistically significant. Multivariate analysis indicated that high clinical risk and high IDE expression were independent prognostic factors for EFS in ALL patients, with risk ratios of 4.254 (95% CI: 1.08017.554, P=0.039) and 21.773 (95% CI: 2.632180.125, P=0.004), respectively. The predictive capacity of the recurrence risk index for prognosis, composed of these two independent prognostic factors, was higher than the current clinical risk stratification (AUCs of 0.892 and 0.741, P=0.009). Conclusion：High expression of the IDE gene is closely associated with poor prognosis in children with ALL.

Key words: Acute lymphoblastic leukemia, IDE, Gene expression, Prognosis