Improvement of Risk Stratification in Acute Lymphoblastic Leukemia Patients by the Determination of the BCR-ABL Gene Expression

Introduction: The BCR-ABL fusion gene [t(9;22) (q34;q11)] occurs in 3–5% of pediatric acute lymphoblastic leukemia (ALL) and predicts a very poor prognosis.
Material and methods: 2 ml samples of bone marrow (BM) and peripheral blood (PB) in EDTA tubes from 24 ALL patients were examined in the molecular biology laboratory of our university with quantitative real-time PCR (qRT-PCR) method for BCR-ABL gene expression. Prognostic factors, like age, leucocyte count, lymphoblast morphology and immunology, absolute lymphoblast count on day 8, remission status on day 33 as well as treatment results were recorded from every patient.
Results: All 24 qRT-PCR analysis for major and minor BCR-ABL gene expression from BM and PB were negative. Immunophenotyping performed in 25 patients revealed common B ALL in 12 patients, T-cell immunology in 3 and pre-B immunophenotype with aberrant myeloid marker expression and/or CD10 negativity in 11 patients. L1 morphology appeared in 85.7% of the pre-B ALL cases, while other immunophenotypes were more likely associated with L2 cytology (62.5%) (p=0.033). Early cortisone response was favourable in 22 patients, all 26 patients achieved complete remission on day 33. Common B immunophenotype was associated with lower WBC (mean 37,770, median 8,200) than other immunophenotypes (WBC mean 63,783, median 50,680).
Conclusions: A new method, the qRT-PCR test was introduced in the investigation of pediatric ALL in our university from 2010. We found a statistically significant correlation between L1 blast morphology and common B immunophenotype. Poor cortisone response was found more frequently in T-cell ALL and pre-B ALL with aberrant myeloid markers or CD10 negativity. All our patients achieved complete remission on day 33. Lower WBC count at presentation was associated with L1 morphology and pre-B immunophenotype.