Background: The Wilms’ tumor gene (WT1) is a tumor suppressor gene encoding for a zinc finger transcription factor, which was originally identified in the pathogenesis of Wilm’s tumor. WT1 expression was described in most of human acute leukemias (AL), and its level was found to be associated with the presence, persistence or reappearance of leukemic hematopoiesis. Conflicting results are reported as far as the prognostic value is concerned. In the present study we analyzed the level of WT1 expression by a Real-Time Quantitative Polymerase Reaction (RQ-PCR) in 68 adult and elderly patients with AL at diagnosis. The aim was to verify if the quantitative WT1 expression was associated to clinic-pathologic features and prognosis of the disease. Materials and Methods: Thirty-one adult (mean age: 46.6 years) and 17 elderly patients (mean age: 68.3 years) with “de novo” AML, and 20 adult patients (mean age: 36.6 years) with newly diagnosed ALL were retrospectively studied. WT1 transcripts from bone marrow blood samples were amplified and quantified using an RQ-PCR assay. WT1 values were normalized with respect to the number of ABL transcripts and expressed as copy numbers every 104 copies of ABL. Standard cytogenetic analysis and complete immunophenotyping by flow cytometry was performed in all cases. Molecular characterization of BCR/ABL rearrangement was also performed in ALL. Adult AML patients were treated with NILG or DCE protocols; elderly AML patients with FLAIG protocol, and adult ALL patients with GIMEMA ALL 0496 protocol. The median follow-up period was 8.2 months for adult AML, 6.6 months for elderly AML and 14 months for adult ALL patients. Results: In adult AML, the mean WT1 level was 6830 (median: 3170, SD: 9370, range: 20-42700). It was higher in males than in females (p=0.04), and tended to be greater in patients younger than 45 years or with low-cytogenetic risk (p=0.1). No association was found between WT1 and the achievement of complete remission (CR). Overall survival (OS) tended to be shorter in patients with WT1 level >3170 than in those with a lower value (p=0.1). In elderly AML, the mean WT1 level was 3330 (median: 1670, SD: 4880, range: 50-16880). It was not associated with patient or leukemic cell characteristics and with CR. OS tended to be longer in patients with WT1 level >1670 than in those with a lower value (p=0.06). In adult ALL, the mean WT1 level was 7820 (median: 906, SD: 19790, range: 4-86770). It was higher in T-ALL than in B-ALL (p=0.02), and tended to be greater in patients older than 45 years (p=0.08) or with a high WBC count (p=0.06). No association was found between WT1 and CR. Disease-free survival (DFS) and OS were shorter for patients with WT1 level >906 than for those with a lower value (p=0.01 and 0.005, respectively). WT1 level was the only independent prognostic factor for both DFS and OS at multivariate analysis. Conclusions: Our results indicate that: 1) the quantitative RQ-PCR analysis allows the detection of WT1 transcripts in all AL cases; 2) the level of WT1 expression, as assessed by RQ-PCR, is of highly prognostic value in patients with adult ALL; 3) the prognostic value of WT1 expression is independent of the leukemic cell mass.
Quantitative analysis of WT1 gene transcripts in adult acute leukemia
PICH, Achille;
2005-01-01
Abstract
Background: The Wilms’ tumor gene (WT1) is a tumor suppressor gene encoding for a zinc finger transcription factor, which was originally identified in the pathogenesis of Wilm’s tumor. WT1 expression was described in most of human acute leukemias (AL), and its level was found to be associated with the presence, persistence or reappearance of leukemic hematopoiesis. Conflicting results are reported as far as the prognostic value is concerned. In the present study we analyzed the level of WT1 expression by a Real-Time Quantitative Polymerase Reaction (RQ-PCR) in 68 adult and elderly patients with AL at diagnosis. The aim was to verify if the quantitative WT1 expression was associated to clinic-pathologic features and prognosis of the disease. Materials and Methods: Thirty-one adult (mean age: 46.6 years) and 17 elderly patients (mean age: 68.3 years) with “de novo” AML, and 20 adult patients (mean age: 36.6 years) with newly diagnosed ALL were retrospectively studied. WT1 transcripts from bone marrow blood samples were amplified and quantified using an RQ-PCR assay. WT1 values were normalized with respect to the number of ABL transcripts and expressed as copy numbers every 104 copies of ABL. Standard cytogenetic analysis and complete immunophenotyping by flow cytometry was performed in all cases. Molecular characterization of BCR/ABL rearrangement was also performed in ALL. Adult AML patients were treated with NILG or DCE protocols; elderly AML patients with FLAIG protocol, and adult ALL patients with GIMEMA ALL 0496 protocol. The median follow-up period was 8.2 months for adult AML, 6.6 months for elderly AML and 14 months for adult ALL patients. Results: In adult AML, the mean WT1 level was 6830 (median: 3170, SD: 9370, range: 20-42700). It was higher in males than in females (p=0.04), and tended to be greater in patients younger than 45 years or with low-cytogenetic risk (p=0.1). No association was found between WT1 and the achievement of complete remission (CR). Overall survival (OS) tended to be shorter in patients with WT1 level >3170 than in those with a lower value (p=0.1). In elderly AML, the mean WT1 level was 3330 (median: 1670, SD: 4880, range: 50-16880). It was not associated with patient or leukemic cell characteristics and with CR. OS tended to be longer in patients with WT1 level >1670 than in those with a lower value (p=0.06). In adult ALL, the mean WT1 level was 7820 (median: 906, SD: 19790, range: 4-86770). It was higher in T-ALL than in B-ALL (p=0.02), and tended to be greater in patients older than 45 years (p=0.08) or with a high WBC count (p=0.06). No association was found between WT1 and CR. Disease-free survival (DFS) and OS were shorter for patients with WT1 level >906 than for those with a lower value (p=0.01 and 0.005, respectively). WT1 level was the only independent prognostic factor for both DFS and OS at multivariate analysis. Conclusions: Our results indicate that: 1) the quantitative RQ-PCR analysis allows the detection of WT1 transcripts in all AL cases; 2) the level of WT1 expression, as assessed by RQ-PCR, is of highly prognostic value in patients with adult ALL; 3) the prognostic value of WT1 expression is independent of the leukemic cell mass.
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