1. Role of MRD in pediatric ALL.

2. Disease-Free Survival DFS - 85,0±6,8% (n=108; ev=6)

4. Risk Group AssignmentWith MRD control STANDARD-RISK GROUP (SR) if available FC MRD < 0,1% or M1/ M2 marrow on day 15 HIGH-RISK GROUP (HR) IR and, if available FC MRD >10% or M3 marrow on day 15 SR if available FC MRD >10% INTERMEDIATE-RISK GROUP (IR) All patients who are not stratified to SR or HR are intermediate risk patients.

5. Assessment of response to treatment • Identify residual leukemia blasts in blood and bone marrow by microscopic analysis on 15 and 33 days. • Morphological assessment can be imprecise. • Measurement of MRD can be used to monitor treatment response much more precisely than morphological screening.

6. Multiparameter Flow Cytometry • Using 3-color flow cytometry on 15 day CD19+CD10+ 13,6% NC CD19+CD10+CD58++ 13,6% NC CD19+CD34+ 0,06% NC CD19+CD34+CD58++ 0,06% NC

7. Patient Information • 67 patients • 64 patients with immunophenotype pre-pre B • 2 patients with pro B immunophenotype • 1 patient with pre B immunophenotype • Age group 6 months-16 years

8. The panel of antibodies to identify aberrant phenotype in children with B-cell leukemia(Prof. NN Tupitcin, senior researcher Grivtsova LY) • CD19/CD10/CD34 • CD19/CD10/CD45 or\andCD19/CD34/CD45 50 pt • 1.Syto16/CD10/CD45/CD19 17pt • 2. CD20/CD10/CD34/CD19 • 3 CD10/CD58/CD34/CD19

9. BM response 15 day M1(< 5,0% blast) • 31 patients • MRD < 0,1%– 19,4% ( 6 of 31) • MRD <0,1-10%– у 74 % (23 of31) • MRD ≥10,0%– у 6,6% (2 of31);

10. BM response 15 day – M2 (5,0-25% blast) • 30 patients • MRD <0,1-10% – у 86,6% (26 of30) • MRD ≥10,0% – у13,4% (4 of30) ;

11. BM response 15 day – M3 (>25% blast) • 6 patients • MRD ≥10,0% - 100% (6 of6)

12. Risk Group

13. Conclusion • We can use MRD as independent prognostic factor in childhood • We can use MRD as tool for risk-group classification during front-line therapy • We can use MRD for adjust treatment intensity.

14. Thanks for you attention.