Prospects for evaluation of the minimal residual disease in the post-induction period in pediatric B-precursor acute lymphoblastic leukemia

Abstract

Relevance.Currently, the assessment of the level of minimal residual disease (MRD) is the standard in evaluating the effectiveness of therapy in acute lymphoblastic leukemia (ALL) in adults and children. Although, the necessity to study MRD at the induction therapy is not in doubt, the prognostic value of MRD in the period after induction is the subject for scientific discussion. Several studies suggest that MRD-positive status after induction chemotherapy associated with poor prognosis, and the reappearance of significant level MRD during follow-up allows impending relapse to be identified and to begin appropriate therapy in low leukemic cells level.Aim– to determine the prognostic value of post-induction MRD on overall (OS), relapse-free (RFS), and event-free (EFS) survival in children with B-precursor ALL who received program treatment at the N.N. Blokhin National Medical Research Centre of Oncology, Ministry of Health of Russia.Materials and methods.The study included 73 pediatric patients with initial B-precursor ALL. The median age of the patients was 5.2 years (from 1 to 16 years). The treatment was according to the ALL IC-BFM 2009 protocol. MRD detected on day 15 and 33 of induction therapy, and day 78 of consolidation beginning. MRD level was determined by flow cytometry method.Results.EFS and RFS were the same for patients with MRD-positive status on 78 day of treatment 76.8 ± 12.3 % and 96.2 ± 2.6 % for MRDnegative (p = 0.06). Detailed assessment of MRD revealed a cohort of high-risk patients with MRD-negative status on 78 day of therapy with 100 % OS (observation time – 6 years).Conclusion.In all risk groups, patients with negative MRD status showed a better survival result, which indicates the possibility of additional stratification by risk groups not only at the induction, but also during a consolidating treatment protocol.