Low burden of minimal residual disease prior to transplantation in children with very high risk acute lymphoblastic leukaemia: The NOPHO ALL2008 experience.

To access publisher's full text version of this article click on the hyperlink belowThe population-based Nordic/Baltic acute lymphoblastic leukaemia (ALL) Nordic Society for Paediatric Haematology and Oncology (NOPHO) ALL2008 protocol combined minimal residual disease (MRD)-driven treatment stratification with very intense first line chemotherapy for patients with high risk ALL. Patients with MRD >= 5% at end of induction or >= 10(-3) at end of consolidation or following two high risk blocks were eligible for haematopoietic cell transplantation (HCT) in first remission. After at least three high risk blocks a total of 71 children received HCT, of which 46 had MRD >= 5% at end of induction. Ten patients stratified to HCT were not transplanted; 12 received HCT without protocol indication. Among 69 patients with evaluable pre-HCT MRD results, 22 were MRD-positive, one with MRD >= 10(-3). After a median follow-up of 5 center dot 5 years, the cumulative incidence of relapse was 23 center dot 5% (95% confidence interval [CI]: 10 center dot 5-47 center dot 7) for MRD-positive versus 5 center dot 1% (95% CI: 1 center dot 3-19 center dot 2), P = 0 center dot 02) for MRD-negative patients. MRD was the only variable significantly associated with relapse (hazard ratio 9 center dot 1, 95% CI: 1 center dot 6-51 center dot 0, P = 0 center dot 012). Non-relapse mortality did not differ between the two groups, resulting in disease-free survival of 85 center dot 6% (95% CI: 75 center dot 4-97 center dot 2) and 67 center dot 4% (95% CI: 50 center dot 2-90 center dot 5), respectively. In conclusion, NOPHO block treatment efficiently reduced residual leukaemia which, combined with modern transplant procedures, provided high survival rates, also among pre-HCT MRD-positive patients.Danish Child Cancer Foundatio