Search

Background:Loss of HLADR and CD34 is a wellknown characteristic of malignant promyelocytes in acute promyelocytic leukemia APL. However, this immunophenotype is not specific for APL. The purpose of this study was to investigate whether further biological characterization of the HLADRnegacute myeloid leukemia patients would allow more clearly define criteria to separate APL from nonAPL patients.Methods:Immunophenotyping, cytogenetics, molecular analyses, and cytomorphology were prospectively performed within routine leukemia diagnostics of 800 patients included in different prospective acute myeloid leukemia multicenter trials.Results:Beside 60 APL, an additional 62 HLADRnegnonAPL patients were identified. The main differential characteristics of HLADRnegnonAPL included high CXCR4 expression in most patients and almost all leukemia cells, a significantly higher proportion of patients presenting with NPM1 mutations as well as the significant association with cuplike nuclear morphology. The biological distinctness of both leukemia subtypes was further emphasized by the complete absence of aberrant CD2 expression and increased leukocyte and platelet counts in HLADRnegnonAPL patients. Even in the CD34possubgroup of HLADRnegnonAPL all those features contributed in at least the same way to the separation from APL.Conclusions:The results of the present study show that an immunophenotypic, molecular, and cytomorphologic separation of both HLADRnegleukemia subgroups is possible indicating that both groups are biologically distinct. © 2009 Clinical Cytometry Society

Between February 1996 and December 2004, the German Leukemia Study Initiative registered 1766 consecutive patients for the acute myeloid leukemia (AML) 96 study, all of whom were diagnosed by central cytomorphology according to the French-American-British (FAB) and the new World Health Organization (WHO) classification. We focused our analysis on the prognostic impact of multilineage dysplasia (MLD) as a new parameter of the WHO classification for AML. We could not confirm the WHO statement that MLD occurs most frequently in older individuals, but we confirmed that MLD is often associated with an unfavorable cytogenetic profile (P < .001). In 1332 individuals receiving intensive AML therapy presence of MLD was negatively correlated with complete remission (P = .001) in univariate, but not in multivariate, analysis. Multivariate analysis of either event-free or overall survival again failed to show an independent prognostic significance of MLD besides age, cytogenetics, and, in part, NPM1/FLT3-ITD mutations. Our data support a reassessment of the WHO classification in the light of a more biologic understanding of AML. This study is registered at www.ClinicalTrials.gov as #NCT00180115.

Between February 1996 and December 2004, the German Leukemia Study Initiative registered 1766 consecutive patients for the acute myeloid leukemia (AML) 96 study, all of whom were diagnosed by central cytomorphology according to the French-American-British (FAB) and the new World Health Organization (WHO) classification. We focused our analysis on the prognostic impact of multilineage dysplasia (MLD) as a new parameter of the WHO classification for AML. We could not confirm the WHO statement that MLD occurs most frequently in older individuals, but we confirmed that MLD is often associated with an unfavorable cytogenetic profile (P< .001). In 1332 individuals receiving intensive AML therapy presence of MLD was negatively correlated with complete remission (P= .001) in univariate, but not in multivariate, analysis. Multivariate analysis of either event-free or overall survival again failed to show an independent prognostic significance of MLD besides age, cytogenetics, and, in part, NPM1/FLT3-ITD mutations. Our data support a reassessment of the WHO classification in the light of a more biologic understanding of AML. This study is registered at www.ClinicalTrials.govas #NCT00180115.

Constitutive activation of the FLT3 receptor tyrosine kinase, either by internal tandem duplication (ITD) of the juxtamembrane region or by point mutations in the second tyrosine kinase domain (TKD), has been described in patients with acute myelogenous leukemia (AML). We analyzed the prevalence and the potential prognostic impact of FLT3 mutations in 979 AML patients. Results were correlated with cytogenetic data and the clinical response. FLT3-ITD mutations were found in 20.4% and FLT3-TKD mutations in 7.7% of the patients. Each mutation was associated with similar clinical characteristics and was more prevalent in patients with normal karyotype. Significantly more FLT3 aberrations were found in patients with FAB M5, and fewer were found in patients with FAB M2 and M6. Although less frequent in patients with cytogenetic aberrations, FLT3-ITDs were found in 13 of 42 patients with t(15;17) and in 9 of 10 patients with t(6;9). The prevalence of the ITD allele on the DNA level was heterogeneous, ranging from faint mutant bands in some patients to predominant mutant bands in others. Based on quantitative analysis, the mutant–wild-type (wt) ratio ranged from 0.03 to 32.56 (median, 0.78). Patients with a high mutant/wt ratio (ie, greater than 0.78) had significantly shorter overall and disease-free survival, whereas survival in patients with ratios below 0.78 did not differ from those without FLT3 aberrations. Multivariate analysis confirmed a high mutant/wt ratio to be a strong independent prognostic factor. Taken together, these data confirm that FLT mutations represent a common alteration in adult AML. Constitutive activation may be associated with monocytoid differentiation. A high mutant/wt ratio in ITD-positive patients appears to have a major impact on the prognostic relevance.

Constitutive activation of the FLT3 receptor tyrosine kinase, either by internal tandem duplication (ITD) of the juxtamembrane region or by point mutations in the second tyrosine kinase domain (TKD), has been described in patients with acute myelogenous leukemia (AML). We analyzed the prevalence and the potential prognostic impact of FLT3 mutations in 979 AML patients. Results were correlated with cytogenetic data and the clinical response. FLT3-ITD mutations were found in 20.4% and FLT3-TKD mutations in 7.7% of the patients. Each mutation was associated with similar clinical characteristics and was more prevalent in patients with normal karyotype. Significantly more FLT3 aberrations were found in patients with FAB M5, and fewer were found in patients with FAB M2 and M6. Although less frequent in patients with cytogenetic aberrations, FLT3-ITDs were found in 13 of 42 patients with t(15;17) and in 9 of 10 patients with t(6;9). The prevalence of the ITD allele on the DNA level was heterogeneous, ranging from faint mutant bands in some patients to predominant mutant bands in others. Based on quantitative analysis, the mutant–wild-type (wt) ratio ranged from 0.03 to 32.56 (median, 0.78). Patients with a high mutant/wt ratio (ie, greater than 0.78) had significantly shorter overall and disease-free survival, whereas survival in patients with ratios below 0.78 did not differ from those without FLT3 aberrations. Multivariate analysis confirmed a high mutant/wt ratio to be a strong independent prognostic factor. Taken together, these data confirm that FLT mutations represent a common alteration in adult AML. Constitutive activation may be associated with monocytoid differentiation. A high mutant/wt ratio in ITD-positive patients appears to have a major impact on the prognostic relevance.

Acute myeloid leukaemia (AML) represents a heterogeneous group of early stem cell malignancies characterized by an uncontrolled expansion of malignant cells blocked at certain stages of myeloid differentiation. Several genetic abnormalities have been described, including translocations involving genes of the CBF family, as well as activating mutations of signal transduction proteins, e.g. N-RAS, K-RAS or the Flt3- receptor tyrosine kinase (RTK). More recently, mutations in the SHP-2 protein, a tyrosine phosphatase involved in RTK signal transduction, have been described in patients with juvenile myelomonocytic leukaemia (JMML) as well as paediatric patients with AM. Only limited data on this aberration are available in older patients. In order to investigate the prevalence and the prognostic relevance of this gene in adults, we analyzed the mutational status of SHP-2 in a cohort of patients with AML. Patients and Methods: DNA samples prepared from bone marrow or peripheral blood samples taken at diagnosis from 977 patients treated in the AML96 protocol of the SHG Dresden were analyzed. Screening for mutations in the mutational hot spot in exon 3 of the PTPN11 gene coding for SHP-2 was performed on a dHPLC system (Transgenomic). Samples with aberrant dHPLC chromatogram were sequenced. Results: In the 977 patients investigated so far, 29 PTPN11 exon 3 mutations were found (3%). All mutations consisted of single base pair exchanges in codons 60–76, mostly affecting codons 69 (n=6), 72 (n=7) and 76 (n=6). Patients with PTPN11 mutations were more likely to have FAB M0 (p= .038) or M5b (p=.045) morphology than negative cases and had a significantly lower prevalence of FLT3-ITD mutations (p= .017). PTPN11 mutations were associated with a normal karyotype in 15/28 evaluable patients, whereas 13 had cytogenetic abnormalities, all of which were either high risk (−7/7q-, n=4; inv3, n=2, complex, n=2, −5, n=1) or intermediate risk (n=4) aberrations. No significant differences were found in the complete remission rate as well as the overall and event free survival, but a trend for a shorter disease free survival was observed in patients with PTPN11 mutations (median 7.8 vs 14.4; p= 0.06) associated with a significantly increased rate of relapse (p= .02). Although not significant yet, a similar trend was seen for patients with normal karyotype. Conclusion: PTPN11 mutations can be found in a small but considerable number of adult patients with AML. Consistent with the data in children, this mutation seems to more prevalent in patients with monosomy 7 and leukemias with monocytic differentiation. Although very preliminary, the data point to a worse prognosis of patients with SHP-2 mutations. We are currently further extending the number of patients and analyze additional exons to delineate the potential prognostic role of this aberration.

Acute myeloid leukaemia (AML) represents a heterogeneous group of early stem cell malignancies characterized by an uncontrolled expansion of malignant cells blocked at certain stages of myeloid differentiation. Several genetic abnormalities have been described, including translocations involving genes of the CBF family, as well as activating mutations of signal transduction proteins, e.g. N-RAS, K-RAS or the Flt3- receptor tyrosine kinase (RTK). More recently, mutations in the SHP-2 protein, a tyrosine phosphatase involved in RTK signal transduction, have been described in patients with juvenile myelomonocytic leukaemia (JMML) as well as paediatric patients with AM. Only limited data on this aberration are available in older patients. In order to investigate the prevalence and the prognostic relevance of this gene in adults, we analyzed the mutational status of SHP-2 in a cohort of patients with AML.