Prognostic relevance of dic(9;20)(p11;q13) in childhood B-cell precursor acute lymphoblastic leukaemia treated with Berlin-Frankfurt-Münster (BFM) protocols containing an intensive induction and post-induction consolidation therapy.

The presence of a dicentric chromosome dic(9;20) has been reported to have an unfavourable prognosis in children with B-cell precursor acute lymphoblastic leukaemia (BCP-ALL). As outcome may be influenced by type and composition of treatment, we analyzed 19 BCP-ALL patients with dic(9;20) who have been treated with ALL-BFM (Berlin-Frankfurt-Münster) protocols that included a 4-drug induction and subsequent consolidation therapy. All patients were good responders to prednisone and in complete remission after induction therapy. Eight patients had no molecular disease after induction and another eight patients had levels < or =10(-4) after consolidation therapy. After a median follow-up of 3.4 years, probabilities of 5-year event-free and overall survival were 75 +/- 11% and 94 +/- 6%, respectively. Of note, there was a tendency for extramedullary disease in case of relapse (two of three relapses with central nervous system involvement). In conclusion, in the context of ALL-BFM protocols dic(9;20)-positivity appeared to have a favourable prognosis, which could be due to a dose- and time-intensified induction and induction consolidation therapy. Given that in vitro studies have shown high cellular sensitivity of dic(9;20)-positive leukemic blasts to l-asparaginase and cytarabine, it is reasonable to speculate that both drugs, as given early during BFM-like induction and consolidation therapy, may have contributed to this good outcome.