The Prognostic Relevance of BAALC and ERG Expression Levels in Cytogenetically Normal Pediatric Acute Myeloid Leukemia

Abstract

Cytogenetic aberrations are important prognostic factors in acute myeloid leukemia (AML). About 45 % of de novo adult AML and 20 % of pediatric AML lack cytogenetic abnormalities, so identification of predictive molecular markers might improve therapy. Mutation status of FLT3, NPM1 genes and gene expression levels of ERG, BAALC have been postulated as possible prognostic markers in pediatric AML with normal karyotype. Pretreatment blood samples from 47 cytogenetically normal AML patients were analysed for BAALC and ERG expression using real time RT-PCR. The patients were dichotomized at BAALC and ERG mean expression into low and high expression based on the median expression as cutoff. BAALC showed high expression in (24/47; 51.1 %) of patients and ERG high expression was detected in (22/47; 46.6 %). With follow-up for 1 year, patients with high BAALC and high ERG had inferior EFS (P = 0.001, P = 0.017 respectively), overall survival (P = 0.001, 0.08 respectively), and low rates of induction remission (P = 0.001, P = 0.0017 respectively) as compared to those with low expression. Also there was significant positive association between high expression of BAALC; ERG and FLT-ITD mutations (P = 0.016; P = 0.007 respectively). Multivariable analysis confirmed that high BAALC expression is an independent risk factor for EFS [HR for EFS 1.9(1.04–3.46) P = 0.037]; and OS [HR OS 1.55(1.7–3.36) P = 0.03]. In conclusion: Over expression of BAALC could predict adverse clinical outcome and may define important risk factor in cytogenetically normal pediatric AML.