Treatment and prognosis of childhood acute lymphoblastic leukemia on protocols ALL-BFM 90, 95 and ALL IC-BFM 2002: a retrospective single-center study from Olomouc, Czech Republic.

Great progress has been made in the diagnostics and treatment of childhood acute lymphoblastic leukemia (ALL) over the past decades. The vast majority of children are cured, however, there is need for further improvement, especially in specific patient subgroups. Our aim was to retrospectively evaluate disease characteristics and treatment outcomes of children with ALL enrolled in a single center into consecutive treatment protocols (ALL-BFM 90, ALL-BFM 95 and ALL IC-BFM 2002) between years 1990 and 2007 and comprehensively summarize diagnostic and therapeutic advances between protocols. In total, 97 patients aged 0 to 18 years were treated for ALL at University Hospital Olomouc in the Czech Republic and steadily high relapse-free survival (RFS), event-free survival (EFS) and overall survival (OS) were observed during the evaluated time period without significant difference between the protocols (RFS 80-86%, EFS 75-83% and OS 84-92%). In conclusion, our center has demonstrated survival rates comparable to leading international study groups for childhood ALL over a substantial period of time. This has been achieved namely due to advances in diagnostics, excellent collaboration on regional, national and international level, quality assurance and high overall standard of care. The acquired experience has been crucial for current participation in the best performing Berlin-Frankfurt-Münster (BFM)-based international trials for childhood ALL.

[Use of flow cytometry in the diagnosis of acute leukemias in childhood]. / Vyuzití prutokové cytometrie v diagnostice akutních leukémií detského veku.

The authors examined, using the method of flow cytometry, 56 children with acute lymphoblastic leukaemia. Leukaemic cells of the bone marrow aspirate and peripheral blood were examined on a FACS 440 apparatus for establishment of the diagnosis before treatment was initiated. Individual immunological subtypes were differentiated by means of a panel of monoclonal antibodies. 80.5% of acute lymphoblastic leukaemias originated from different developmental stages of B cells, 12.5% were formed by leukaemias from T cells and 7% were non-differentiated leukaemias. The mean follow-up period in the group was 33 months. According to the therapeutic results children with leukaemia ensuing from precursors of B cells had a more favourable prognosis than children with T leukaemia and children with non-differentiated leukaemia. Quantitative examination of nuclear DNA of leukaemic cells revealed in 55% of the patients of the group aneuploidy with clear predominance of hyperdiploidy, 45% of the patients suffered from diploidy. The least number of relapses was recorded in the investigation period in children with hyperploid acute lymphoblastic leukaemia. The proliferating activity of leukaemic blasts was expressed by the number of cells in the S + G2M stage of the cellular cycle and was higher in the bone marrow than in peripheral blood but did not differ in individual immunological subtypes or in diploid leukaemias. The authors were not able to prove its prognostic importance. Flow cytometry is a rapid and sensitive diagnostic method which makes it possible to characterize more satisfactorily the heterogeneous group of acute lymphoblastic leukaemias.

CD2-positive B-cell precursor acute lymphoblastic leukemia with an early switch to the monocytic lineage.

Switches from the lymphoid to myeloid lineage during B-cell precursor acute lymphoblastic leukemia (BCP-ALL) treatment are considered rare and thus far have been detected in MLL-rearranged leukemia. Here, we describe a novel BCP-ALL subset, switching BCP-ALL or swALL, which demonstrated monocytosis early during treatment. Despite their monocytic phenotype, 'monocytoids' share immunoreceptor gene rearrangements with leukemic B lymphoblasts. All swALLs demonstrated BCP-ALL with CD2 positivity and no MLL alterations, and the proportion of swALLs cases among BCP-ALLs was unexpectedly high (4%). The upregulation of CEBPα and demethylation of the CEBPA gene were significant in blasts at diagnosis, prior to the time when most of the switching occurs. Intermediate stages between CD14(neg)CD19(pos)CD34(pos) B lymphoblasts and CD14(pos)CD19(neg)CD34(neg) 'monocytoids' were detected, and changes in the expression of PAX5, PU1, M-CSFR, GM-CSFR and other genes accompanied the switch. Alterations in the Ikaros and ERG genes were more frequent in swALL patients; however, both were altered in only a minority of swALLs. Moreover, switching could be recapitulated in vitro and in mouse xenografts. Although children with swALL respond slowly to initial therapy, risk-based ALL therapy appears the treatment of choice for swALL. SwALL shows that transdifferentiating into monocytic lineage is specifically associated with CEBPα changes and CD2 expression.