Background: FMS-Like Tyrosine kinase 3 (FLT3) plays an important role in early stages of hematopoiesis. FLT3
stimulation enhances proliferation and reduces apoptosis. One potential mechanism of FLT3 involvement in
leukemia is over expression of its wild type and its ligand. The FLT3 protein is highly expressed in most patients
with AML. In patients with ALL, FLT3 protein is highly expressed in up to 50% of leukemic blasts. Here, we
aimed to evaluate the frequency of FLT3 protein expression in pediatric patients with ALL at South Egypt Cancer
Institute, Assiut University, Egypt.
Method: FLT3 surface protein expression on leukemic blasts was detected by flowcytometry of 101 denovo
pediatric acute lymphoblastic leukemia patients. High FLT3 expression considered when ≥20% of malignant cells
expressed CD135 and low FLT3 expression considered when <20% of malignant cells expressed CD135. Relation
between FLT3 expression and other clinical and laboratory findings were studies.
Results: High FLT3 expression was found in 47.5% of patients {39/74(52.7%) of precursor B-ALL and
9/27(33.3%) of precursor T-ALL}. High FLT3 level was significantly expressed in patients with the low risk age
group (p<0.001), patients who had no mediastinal mass, patients without lymphomatous features at presentation and
patients with no CNS involvement at presentation (p<0.001). 75% of patients with high FLT3 expression had TLC
<50.000×109 (p=0.004).
Conclusion: High FLT3 protein expression may be more commonly associated to favorable criteria of our ALL
patients.