Adult T-cell acute lymphoblastic leukemia:: biologic profile at presentation and correlation with response to induction treatment in patients enrolled in the GIMEMA LAL 0496 protocol

Between 1996 and 2000, 90 newly diagnosed adult patients with T-acute lymphoblastic leukemia (T-ALL) were registered in the Gruppo Italiano Malattie Emato-logiche dell'Adulto (GIMEMA) Leucemia Acuta Limfoide (LAL) 0496 protocol. Cases were centrally processed for morphology, immunophenotype, cytogenetics, molecular biology, and multidrug resistance (MDR). Twenty-two patients were females and 68 were males. Four percent of cases were pro-T, 47% pre-T, 39% cortical T, and 10% mature T-ALL. Fifty-six percent of patients with pro-T + pre-T-ALL achieved complete remission (CR) compared with 91% for cortical + mature cases (P = .002). CD34 expression was associated with a significantly lower CR rate: 54% versus 84% (P = .009). Thirty-one (36.5%) of 85 patients had an abnormal karyotype, the most common abnormality (15%) being a partial del(6q). The cytogenetic profile did not impact on CR achievement. MDR1 function, present in 26% of cases, correlated significantly with CR achievement (P = .004). A highly significant (P = .001) difference in CR rate was observed between patients who did not express the CD13/CD33/CD34 antigens and were MDR functionally negative (96%) compared with patients positive for at least one of these markers (57%). Multivariate analysis showed an impact on CR achievement for CD33 expression and MDR1 function. An extensive biologic workup of adult T-ALL cases at presentation is recommended in order to design tailored therapeutic strategies aimed at improving CR rates.