Rapid molecular response during early induction chemotherapy predicts a good outcome in childhood acute lymphoblastic leukemia

Early response to therapy is an Independent prognostic factor in childhood acute lymphoblastic leukemia. Although most patients have rapid early respo nses, as detected by morphology, 15% to 20% of patients have relapses. The authors evaluated residual disease by molecular methods on day 15 of minima l residual disease (MRD) therapy and compared these data with their recentl y established MRD-based risk stratification, defined by MRD levels 5 weeks after induction treatment and before consolidation. All 68 children treated according to current Berlin-Frankfurt-Munster (BFM) protocols went into mo rphologically complete remission after induction. There was a significant d ifference In outcome between children with rapid disease clearance and thos e with high levels of day-15 MRD (P = .035), Among patients with high level s of day-15 MRD, only the MRD-based risk stratification was predictive of t he outcome. All patients with negative or low day-15 MRD had excellent prog noses and were In the MRD based low risk group. Thus, after only 2 weeks of treatment, the authors were able to identify a patient population of 20% w ho may benefit from the least intensive treatment. (C) 2000 by The American Society of Hematology.