Background: In children, acute lymphoblastic leukemia (ALL) serves as the most prevalent blood malignancy. Based on the American Cancer Society, there were 1580 fatalities and 5690 reported as new cases of ALL in adults and children in the United States (US) in 2021. Aim of the Work: The objective of this research is to examine the expression levels of the FoxO3a gene in bone marrow samples of pediatric patients with ALL using real-time polymerase chain reaction (PCR), in order to develop a newly targeted treatment for the disease and determine whether there is a relationship between the expression levels of FoxO3a gene, the clinical presentation and laboratory data of these patients. Subjects and Methods: This research was performed on fifty-three recently diagnosed pediatric ALL cases, according to the 2016 World Health Organization (WHO) categorization (36 were B-acute lymphoblastic leukemia (B-ALL) versus 17were T-acute lymphoblastic leukemia (T-ALL)) and 30 healthy participants age and sex matched to cases as a control group. These individuals were admitted at the South Egypt Cancer Institute (SECI), Assiut University in the period from June 2020 to December 2021. Results: FoxO3a gene was significantly downregulated in ALL patients. Statistically significant correlations among downregulation of FoxO3a gene, hepatosplenomegaly, and the higher percentage of peripheral (PB) blast cells were recorded.

Conclusion: FoxO3a gene acts as tumor suppressor gene, thus rendering FoxO3a gene as potential target for treating ALL as one of hematopoietic malignancies