Prognostic implications of mutations and expression of the Wilms tumor 1 (WT1) gene in adult acute T-lymphoblastic leukemia

Background

The role of the Wilms tumor 1 gene (WT1) in acute leukemias has been underscored by mutations found in acute myeloid leukemia identifying patients with inferior survival. Furthermore, aberrant expression of WT1 in acute myeloid leukemia was associated with an increased risk of relapse. No larger studies have performed a combined approach including WT1 mutation and expression analyses in acute T-lymphoblastic leukemia.

Design and Methods

We analyzed the WT1 mutations and the expression status in a total of 252 consecutive adult patients with newly diagnosed T-lymphoblastic leukemia, who were registered on the GMALL 06/99 and 07/03 protocols and had sufficient material available. The GMALL protocols included intensive chemotherapy as well as stem cell transplantation according to a risk-based model with indication for stem cell transplantation in first complete remission for early and mature T-lymphoblastic leukemia patients; patients with thymic T-lymphoblastic leukemia were allocated to a standard risk group and treated with intensive chemotherapy.

Results

Twenty of the 238 patients analyzed had WT1 mutations (WT1mut) in exon 7. WT1mut cases were characterized by immature features such as an early immunophenotype and higher WT1 expression. In thymic T-lymphoblastic leukemia, WT1mut patients had an inferior relapse-free survival compared to WT1 wild-type patients. T-lymphoblastic leukemia patients with aberrant WT1 expression (high or negative) showed a higher relapse rate and an inferior outcome compared to patients with intermediate WT1 expression. In the standard risk group of thymic T-lymphoblastic leukemia, aberrant WT1 expression was predictive for an inferior relapse-free survival as compared to patients with intermediate expression. In multivariate analysis, WT1 expression was of independent prognostic significance for relapse-free survival.

Conclusions

WT1 mutations were associated with an inferior relapse-free survival in standard risk thymic T-lymphoblastic leukemia patients. Moreover, altered expression associated with inferior outcome also suggests a role of WT1 in T-lymphoblastic leukemia and the potential use of molecularly-based treatment stratification to improve outcome.     

Acquired mutations in ASXL1 in acute myeloid leukemia: prevalence and prognostic value

Somatic mutations in the additional sex comb-like 1 (ASXL1) gene have been described in various types of myeloid malignancies, including acute myeloid leukemia. Analysis of novel markers, such as ASXL1 mutations, in independent clinical trials is indispensable before considering them for clinical decision-making. We analyzed 882 well-characterized acute myeloid leukemia cases to determine the prevalence and prognostic impact of ASXL1 exon12 mutations. Truncating ASXL1 mutations were present in 46 cases (5.3%). ASXL1 mutations were inversely associated with FLT3 internal tandem duplications and mutually exclusive with NPM1 mutations. ASXL1 mutations were an unfavorable prognostic factor as regards survival (median overall survival 15.9 months vs. 22.3 months; P=0.019), with a significantly lower complete response rate (61% vs. 79.6%; P=0.004). In multivariate analyses, ASXL1 mutations were independently associated with inferior poor overall survival (HR 1.52, P=0.032). In conclusion, ASXL1 mutations are common mutations in acute myeloid leukemia and indicate a poor therapy outcome.     

Mutations of PHF6 are associated with mutations of NOTCH1, JAK1 and rearrangement of SET-NUP214 in T-cell acute lymphoblastic leukemia

Background

Mutations in the PHF6 gene were recently described in patients with T-cell acute lymphoblastic leukemia and in those with acute myeloid leukemia. The present study was designed to determine the prevalence of PHF6 gene alterations in T-cell acute lymphoblastic leukemia.

Design and Methods

We analyzed the incidence and prognostic value of PHF6 mutations in 96 Chinese patients with T-cell acute lymphoblastic leukemia. PHF6 deletions were screened by real-time quantitative polymerase chain reaction and array-based comparative genomic hybridization. Patients were also investigated for NOTCH1, FBXW7, WT1, and JAK1 mutations together with CALM-AF10, SET-NUP214, and SIL-TAL1 gene rearrangements.

Results

PHF6 mutations were identified in 11/59 (18.6%) adult and 2/37 (5.4%) pediatric cases of T-cell acute lymphoblastic leukemia, these incidences being significantly lower than those recently reported. Although PHF6 is X-linked and mutations have been reported to occur almost exclusively in male patients, we found no sex difference in the incidences of PHF6 mutations in Chinese patients with T-cell acute lymphoblastic leukemia. PHF6 deletions were detected in 2/79 (2.5%) patients analyzed. NOTCH1 mutations, FBXW7 mutations, WT1 mutations, JAK1 mutations, SIL-TAL1 fusions, SET-NUP214 fusions and CALM-AF10 fusions were present in 44/96 (45.8%), 9/96 (9.4%), 4/96 (4.1%), 3/49 (6.1%), 9/48 (18.8%), 3/48 (6.3%) and 0/48 (0%) of patients, respectively. The molecular genetic markers most frequently associated with PHF6 mutations were NOTCH1 mutations (P=0.003), SET-NUP214 rearrangements (P=0.002), and JAK1 mutations (P=0.005). No differences in disease-free survival and overall survival between T-cell acute lymphoblastic leukemia patients with and without PHF6 mutations were observed in a short-term follow-up.

Conclusions

Overall, these results indicate that, in T-cell acute lymphoblastic leukemia, PHF6 mutations are a recurrent genetic abnormality associated with mutations of NOTCH1, JAK1 and rearrangement of SET-NUP214.     

NOTCH1 mutations in +12 chronic lymphocytic leukemia (CLL) confer an unfavorable prognosis, induce a distinctive transcriptional profiling and refine the intermediate prognosis of +12 CLL

Trisomy 12, the third most frequent chromosomal aberration in chronic lymphocytic leukemia (CLL), confers an intermediate prognosis. In our cohort of 104 untreated patients carrying +12, NOTCH1 mutations occurred in 24% of cases and were associated to unmutated IGHV genes (P=0.003) and +12 as a sole cytogenetic abnormality (P=0.008). NOTCH1 mutations in +12 CLL associated with an approximately 2.4 fold increase in the risk of death, a significant shortening of survival (P<0.01) and proved to be an independent predictor of survival in multivariate analysis. Analogous to +12 CLL with TP53 disruption or del(11q), NOTCH1 mutations in +12 CLL conferred a significantly worse survival compared to that of +12 CLL with del(13q) or +12 only. The overrepresentation of cell cycle/proliferation related genes of +12 CLL with NOTCH1 mutations suggests the biological contribution of NOTCH1 mutations to determine a poor outcome. NOTCH1 mutations refine the intermediate prognosis of +12 CLL.     

FBXW7 and NOTCH1 mutations in childhood T cell acute lymphoblastic leukaemia and T cell non-Hodgkin lymphoma

Mutation analysis of FBXW7 and NOTCH1 genes was performed in 55 T cell acute lymphoblastic leukaemia (T-ALL) and 14 T cell non-Hodgkin lymphoma (T-NHL) patients who were treated on the Japan Association of Childhood Leukaemia Study (JACLS) protocols ALL-97 and NHL-98. FBXW7 and/or NOTCH1 mutations were found in 22 (40·0%) of 55 T-ALL and 7 (50·0%) of 14 T-NHL patients. FBXW7 mutations were found in 8 (14·6%) of 55 T-ALL and 3 (21·4%) of 14 T-NHL patients, and NOTCH1 mutations in 17 (30·9%) of 55 T-ALL and 6 (42·9%) of 14 T-NHL patients. Three (5·4%) T-ALL and two (1·4%) T-NHL patients had mutations in both FBXW7 and NOTCH1 . FBXW7 mutations included one insertion, one deletion, one deletion/insertion and nine missense mutations. NOTCH1 mutations were detected in the heterodimerization domain (HD) in 15 cases, in the PEST domain in seven cases, and in both the HD and PEST domains in one case. Five-year event-free survival and overall survival for patients with FBXW7 and/or NOTCH1 mutations were 95·5% (95% CI, 71·9–99·4%) and 100% respectively, suggesting that T-ALL patients with FBXW7 and/or NOTCH1 mutation represent a good prognosis compared to those without FBXW7 and/or NOTCH1 mutations (63·6%, P  = 0·007 and 78·8%, P  = 0·023, respectively).     

Prognostic implications of NPM1 mutations and FLT3 internal tandem duplications in Egyptian patients with cytogenetically normal acute myeloid leukemia

Nucleophosmin (NPM1) and fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) gene mutations represent the most frequent molecular aberrations in patients with cytogenetically normal-acute myeloid leukemia (CN-AML). We analyzed the prognostic impact of these mutations and their interactions in adults with CN-AML. NPM1 mutation (NPM1mut) and FLT3-ITD mutation (FLT3-ITD+) were analyzed by polymerase chain reaction and GeneScan assays of bone marrow samples obtained from newly diagnosed 104 CN-AML patients. FLT3-ITD+ and NPM1mut were detected in 36 (34.6%) and 30 (28.8%) out of 104 subjects, respectively, 16 cases (15.4%) had double NPM1mut/FLT3-ITD+. The incidence of FLT3-ITD+ was significantly higher in the NPM1mut group than in the NPM1 wild (NPM1wt) group (P = 0.018). Statistical analysis revealed that isolated NPM1mut group had a better clinical outcomes in terms of higher complete response (CR) rate (P = 0.01) and a trend towards favorable overall survival (OS) and disease-free survival (DFS) (P = 0.28, 0.40, respectively). In contrast, the isolated FLT3-ITD+ group had an unfavorable outcome in terms of lower CR rate (P = 0.12), shorter OS, and DFS (P < 0.0001 for both). The NPM1mut/FLT3-ITD-group had the best OS and DFS, while the NPM1wt/FLT3-ITD+ group had the worst OS and DFS than other groups (NPM1mut/FLT3-ITD+ or NPM1wt/FLT3-ITD?) (P < 0.0001 for both). Multivariate Cox regression analysis showed that age and FLT3/ITD+ were independent poor prognostic factors for OS (P = 0.006, <0.0001, respectively), while FLT3/ITD+ was independent predictor for DFS (P = 0.04). However, NPM1mut did not have a significant impact on OS and DFS. In conclusion, adult patients with CN-AML carrying isolated NPM1mut and isolated FLT3-ITD+ exhibit different clinical outcomes than those with NPM1mut/FLT3-ITD+ or NPM1wt/FLT3-ITD?. Patients with NPM1mut/FLT3-ITD? had the best prognosis in terms of higher CR, OS, and DFS, while those with NPM1mut/FLT3-ITD+ had the worst CR rate, and NPM1wt/FLT3-ITD+ had the lowest OS and DFS.     

Prognostic value of p53 gene mutations and the product expression in de novo acute myeloid leukemia

In acute myeloid leukemia (AML), p53 mutations are reportedly infrequent but associated with a poor prognosis. The majority of mutations are missense mutations, which generally lead to accumulation of nuclear p53 protein. However, the prognostic significance of the accumulation remains unknown in AML. In this study, we compared the prognostic value of p53 mutations versus accumulation of the product. p53 mutations were found in 9 (4.5%) of 200 patients with de novo AML. The p53 mutation detectable (mutation+) group had a worse prognosis (p = 0.0009) than the mutation not detectable (mutation-) group. Multivariate analysis showed that the p53 mutation was an independent factor (p = 0.005) for short overall survival as well as 60 yr or older (p = 0.001) and unfavorable karyotypes (p = 0.001). In 79 of the 200 patients, the expression of p53 was studied by immunocytochemistry (ICC) using anti-p53 monoclonal antibody (DO-7). All samples carrying missense mutations (N = 6) were positive for ICC in over 15% of nuclei of each sample, chosen as the optimized cutoff value of p53 accumulation. Accumulation was thus found in 14 of the 79 patients. However, there was no prognostic difference according to the accumulation, because the mutation-/accumulation+ group (N = 8) tended to have a good prognosis. These findings indicate that molecular detection of p53 mutations yields better prognostic information than ICC. In a subset of AML, p53 protein might be accumulated without mutation presumably due to upstream signals of p53.