Myeloid/T-cell acute lymphoblastic leukemia in children and adults.

Until recently, few molecular aberrations were recognized in T-cell acute lymphoblastic leukemia (T-ALL) and they were restricted to aberrations involving the T-cell receptor (TCR). The introduction of powerful technologies has allowed to identify novel rearrangements. In this context, we have performed a gene expression profiling analysis on a relatively large cohort (n=69) of adult patients with a diagnosis of T-ALL. By unsupervised clustering, we identified 5 subgroups. Of these, one branch included 7 patients (10%) whose gene expression profile resembled that of AML. These cases were characterized by the overexpression of a large set of myeloid-related genes, as well as of miR-223. Finally, these patients appear to have an unfavorable clinical course. This newly identified subset of T-ALL cases partly resembles the so-called ETP (early T-precursor) pediatric subgroup: both age groups have in fact a peculiar gene expression profile, an unfavorable outcome and an incidence of about 10%.