NKX2-5, SIL/TAL and TLX3/HOX11L2 expression in Egyptian pediatric T-cell acute lymphoblastic leukemia.

Aim: Cohorts of T-cell acute lymphoblastic leukemia (T-ALL) patients show regional geographic differences in incidence, biological features and clinical outcome, implying that in different populations, cases may harbor different genetic lesions than those reported elsewhere. In this study, we prospectively evaluated the frequency and the clinical relevance of NKX2-5, TLX3/HOX11L2 and SIL/TAL expression in Egyptian childhood T-ALL.

Methods: NKX2-5, TLX3/HOX11L2 and SIL/TAL expression were tested in peripheral blood and/or bone marrow of 83 newly diagnosed Egyptian childhood T-ALL patients.

Results: NKX2-5 expression was detected in 11/83 cases (13%), TLX3/HOX11L2 (5/83, 6%) and SIL/TAL (4/83, 5%). Initial central nervous system involvement was significantly higher in the NKX2-5 positive versus negative patients (P = 0.009). The follow-up period was a median of 65.5 months. The 5-year leukemia-free and event-free survival rates of the whole T-ALL population were 70 ± 6% and 58 ± 6%, respectively. The 5-year leukemia-free and event-free survival rates of NKX2-5 were 86 ± 13% and 60 ± 16%, respectively. There were no statistically significant differences in clinical presentation, biological features, initial response to chemotherapy, or subsequent treatments between the subgroups and the total population.

Conclusion: Egyptian T-ALL cases seemed to have a different genetic pattern compared to other populations, with a lower incidence of TLX3/HOX11L2 and SIL/TAL but a higher incidence of NKX2-5 expression than recorded in Western countries.