Identification of a new subgroup of adult acute T-lymphoblastic leukemia (T-ALL) with a very favorable outcome using low ERG and BAALC expression

7014 Background: High expression of the oncogenic ETS transcription factor ERG is an independent adverse prognostic factor in T-ALL and acute myeloid leukemia (AML). The gene BAALC similarly shows high expression in hematopoietic progenitors, downregulation with onset of differentiation, and prognostic significance in AML. Therefore, we assessed whether combined expression of ERG and BAALC would better predict outcome in T-ALL. Methods: ERG and BAALC mRNA expression was determined by realtime RT-PCR in pretherapy bone marrow of 152 adults with newly diagnosed T-ALL treated on German ALL protocols (05/93, 06/99). Patients (pts) were designated low (n=76) or high (n=76) ERG expressers based on median ERG expression and as low (n=111) or high (n=37) BAALC grouping the lower quartiles 1–3 vs. quartile 4. HOX11 and HOX11L2 expression was determined and immunophenotyping differentiated 3 T-ALL groups (early, thymic, mature). Results: High BAALC expression correlated with immature T-ALL with a higher frequency o...