[Show abstract][Hide abstract] ABSTRACT: To evaluate the incidence and clinical impact of WT1 gene mutations in younger adult patients with cytogenetically normal acute myeloid leukemia (CN-AML), sequencing of the complete coding region was performed in diagnostic samples from 617 patients who were treated on 3 German-Austrian AML Study Group protocols. WT1 mutations were identified in 78 (12.6%) of the 617 patients; mutations clustered in exon 7 (54 of 78) and exon 9 (13 of 78), but also occurred in exons 1, 2, 3, and 8. WT1 mutations were significantly associated with younger age, higher serum lactate dehydrogenase levels, higher blood blast counts, and the additional presence of FLT3-ITD (P < .001) and CEBPA mutations (P = .004). There was no difference in relapse-free survival and overall survival between patients with (WT1(mut)) or without WT1 mutations. Subset analysis showed that patients with the genotype WT1(mut)/FLT3-ITD(pos) had a lower complete remission rate (P = .003) and an inferior relapse-free survival (P = .006) and overall survival (P < .001) compared with those with the genotype WT1(mut)/FLT3-ITD(neg). In conclusion, in our large cohort of younger adults with CN-AML, WT1 mutation as a single molecular marker did not impact on outcome. However, our data suggest a negative impact of the genotype WT1(mut)/FLT3-ITD(pos).
[Show abstract][Hide abstract] ABSTRACT: Therapy-associated myelodysplastic syndromes and acute myeloid leukaemia (t-AML/MDS) following high dose chemotherapy are significant problems, with a cumulative incidence of 20% or more in myeloablative treatment regimen. Retrospective findings indicated that t-AML/MDS associated genetic aberrations can be observed directly after exposure to chemotherapy and can precede t-AML by several months. To determine the incidence of post-therapeutic aberrations and their predictive value, we prospectively investigated 316 samples of 95 patients with non-Hodgkin lymphoma (NHL) who were treated with intermediate and high dose chemotherapy (Arm A and B of the megaCHOEP (cyclophosphamide, doxorubicin, etoposide, vincristine, prednisolone) trial of the German High Grade NHL study group). Molecular aberrations (RUNX1/RUNX1T1, PML-RARA, CBFB-MYH11, MLL-MLLT1, BCR-ABL1) were observed in 33.3% (Arm A) and 55.4% (Arm B) of patients and in 14.9% and 28.7% of respective samples. Cytogenetic analysis of 53 NHL patients after high dose therapy showed frequent chromosomal breakage. Clonal aberrations were found in three patients. None of these patients developed a t-AML/MDS during a 3-year clinical follow up period. We concluded that the high incidence of genetic aberrations reflected a dose-dependent, transient therapy-induced genetic damage which is not predictive of a t-AML/MDS.
British Journal of Haematology 05/2008; 141(1):52-9. DOI:10.1111/j.1365-2141.2008.07023.x · 4.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Targeted disruption of a highly conserved distal enhancer reduces expression of the PU.1 transcription factor by 80% and leads to acute myeloid leukemia (AML) with frequent cytogenetic aberrations in mice. Here we identify a SNP within this element in humans that is more frequent in AML with a complex karyotype, leads to decreased enhancer activity, and reduces PU.1 expression in myeloid progenitors in a development-dependent manner. This SNP inhibits binding of the chromatin-remodeling transcriptional regulator special AT-rich sequence binding protein 1 (SATB1). Overexpression of SATB1 increased PU.1 expression, and siRNA inhibition of SATB1 downregulated PU.1 expression. Targeted disruption of the distal enhancer led to a loss of regulation of PU.1 by SATB1. Interestingly, disruption of SATB1 in mice led to a selective decrease of PU.1 RNA in specific progenitor types (granulocyte-macrophage and megakaryocyte-erythrocyte progenitors) and a similar effect was observed in AML samples harboring this SNP. Thus we have identified a SNP within a distal enhancer that is associated with a subtype of leukemia and exerts a deleterious effect through remote transcriptional dysregulation in specific progenitor subtypes.