Clinical significance of immunophenotypic markers in pediatric T-cell acute lymphoblastic leukemia.

Background: Cell-marker profiling has led to conflicting conclusions about its prognostic significance in T-ALL.

Aim: To investigate the prevalence of the expression of CD34, CD10 and myeloid associated antigens (CD13/ CD33) in childhood T-ALL and to relate their presence to initial clinical and biologic features and early response to therapy.

Patients And Methods: This study included 67 consecutive patients with newly diagnosed T-ALL recruited from the Children's Cancer Hospital in Egypt during the time period from July 2007 to June 2008. Immunophenotypic markers and minimal residual disease (MRD) were studied by five-color flow cytometry.

Results: The frequency of CD34 was 34.9% , CD10 33.3% , while CD13/CD33 was 18.8%. No significant association was encountered between CD34, CD10 or myeloid antigen positivity and the presenting clinical features as age, sex, TLC and CNS leukemia. Only CD10(+) expression had significant association with initial CNS involvement (p=0.039). CD34 and CD13/CD33 expression was significantly associated with T-cell maturation stages (p<0.05). No relationship was observed for age, TLC, gender, NCI risk or CNS involvement with early response to therapy illustrated by BM as well as MRD day 15 and day 42. CD34(+), CD13/CD33(+) and early T-cell stage had high MRD levels on day 15 that was statistically highly significant (p<0.01), but CD10(+) had statistically significant lower MRD level on day 15 (p=0.049). However, only CD34 retained its significance at an MRD cut-off level of 0.01%.

Conclusions: CD34, CD10, CD13/CD33 expression, as well as T-cell maturation stages, may have prognostic significance in pediatric T-ALL as they have a significant impact on early clearance of leukemic cells detected by MRD day 15.