Characterization of children with FLT3-ITD acute myeloid leukemia: a report from the AIEOP AML-2002 study group.

Recurrent molecular markers have been routinely used in acute myeloid leukemia (AML) for risk assessment at diagnosis, whereas their post-induction monitoring still represents a debated issue. We evaluated the prognostic value and biological impact of minimal residual disease (MRD) and of the allelic ratio (AR) of FLT3-internal-tandem duplication (ITD) in childhood AML. We retrospectively screened 494 children with de novo AML for FLT3-ITD mutation, identifying 54 harboring the mutation; 51% of them presented high ITD-AR at diagnosis and had worse event-free survival (EFS, 19.2 versus 63.5% for low ITD-AR, <0.05). Forty-one percent of children with high levels of MRD after the 1st induction course, measured by a patient-specific real-time-PCR, had worse EFS (22.2 versus 59.4% in low-MRD patients, P<0.05). Next, we correlated these parameters with gene expression, showing that patients with high ITD-AR or persistent MRD had characteristic expression profiles with deregulated genes involved in methylation and acetylation. Moreover, patients with high CyclinA1 expression presented an unfavorable EFS (20.3 versus 51.2% in low CyclinA1 group, P<0.01). Our results suggest that ITD-AR levels and molecular MRD should be considered in planning clinical management of FLT3-ITD patients. Different transcriptional activation of epigenetic and oncogenic profiles may explain variability in outcome among these patients, for whom novel therapeutic approaches are desirable.

Immunophenotyping of acute leukemia and lymphoproliferative disorders: a consensus proposal of the European LeukemiaNet Work Package 10.

The European LeukemiaNet (ELN), workpackage 10 (WP10) was designed to deal with diagnosis matters using morphology and immunophenotyping. This group aimed at establishing a consensus on the required reagents for proper immunophenotyping of acute leukemia and lymphoproliferative disorders. Animated discussions within WP10, together with the application of the Delphi method of proposals circulation, quickly led to post-consensual immunophenotyping panels for disorders on the ELN website. In this report, we established a comprehensive description of these panels, both mandatory and complementary, for both types of clinical conditions. The reason for using each marker, sustained by relevant literature information, is provided in detail. With the constant development of immunophenotyping techniques in flow cytometry and related software, this work aims at providing useful guidelines to perform the most pertinent exploration at diagnosis and for follow-up, with the best cost benefit in diseases, the treatment of which has a strong impact on health systems.

New methodologic approaches for immunophenotyping acute leukemias.

BACKGROUND AND OBJECTIVES: Flow cytometry is nowadays the preferred method for immunophenotypic identification, enumeration and characterization of blast cells at diagnosis. Despite widespread application of standardized protocols, inter-laboratory reproducibility has still not been achieved. The complexity of diagnosis and evaluation of minimal residual disease, in immunophenotyping acute leukemia, demands the use of a test that provides all the necessary information. DATA SOURCES AND METHODS: The information given here is derived from the experience of the authors and from literature files. The most relevant studies with adequate conclusions were considered. We report on the current status of multiparametric immunophenotyping using simultaneous three and four-color staining and the applications of this technique. RESULTS: Multiparametric immunophenotyping is a powerful method for achieving a clear discrimination between normal and pathologic cells. The specific identification of leukemic cells by immunologic gating forms the basis for immunophenotypic diagnosis, classification as well as prognostic evaluation of patients with acute leukemias. The performance of the procedure with regards to the panels of reagents and the analytic processes, is necessarily different in lymphoblastic and myeloblastic leukemias, since the diagnostic questions are different. Phenotypic information should be specifically provided for the blast cells and antigen expression should preferably be reported in quantitative units and CV. This would allow a standardized cross evaluation of immunophenotypic results between different investigators and laboratories. INTERPRETATION AND CONCLUSIONS: Recent reports indicate that phenotypic aberrations reflect genetic abnormalities of leukemic cells and therefore their definition and identification is of clinical relevance not only for minimal residual disease monitoring but also for subclassifying acute myeloid and lymphocytic leukemias.