Impact of complex NOTCH1 mutations on survival in paediatric T-cell leukaemia

<p>Abstract</p> <p>Background</p> <p>Molecular alterations occur frequently in T-ALL and the potential impact of those abnormalities on outcome is still controversial. The current study aimed to test whether <it>NOTCH1 </it>mutations and additional molecular abnormalities would impact T-ALL outcome in a series of 138 T-ALL paediatric cases.</p> <p>Methods</p> <p>T-ALL subtypes, status of <it>SIL-TAL1 </it>fusion, ectopic expression of <it>TLX3</it>, and mutations in <it>FBXW7</it>, <it>KRAS</it>, <it>PTEN </it>and <it>NOTCH1 </it>were assessed as overall survival (OS) and event-free survival (EFS) prognostic factors. OS and EFS were determined using the Kaplan-Meier method and compared using the log-rank test.</p> <p>Results</p> <p>The frequencies of mutations were 43.5% for <it>NOTCH1</it>, while <it>FBXW7</it>, <it>KRAS </it>and <it>PTEN </it>exhibited frequencies of 19.1%, 9.5% and 9.4%, respectively. In 78.3% of cases, the coexistence of <it>NOTCH1 </it>mutations and other molecular alterations was observed. In multivariate analysis no statistical association was revealed between <it>NOTCH1 </it>mutations and any other variable analyzed. The mean length of the follow-up was 68.4 months and the OS was 50.7%. <it>SIL-TAL1 </it>was identified as an adverse prognostic factor. <it>NOTCH1 </it>mutation status was not associated with outcome, while the presence of <it>NOTCH1 </it>complex mutations (indels) were associated with a longer overall survival (<it>p </it>= 0.031) than point mutations.</p> <p>Conclusion</p> <p><it>NOTCH1 </it>mutations alone or in combination with <it>FBXW7 </it>did not impact T-ALL prognosis. Nevertheless, complex <it>NOTCH1 </it>mutations appear to have a positive impact on OS and the <it>SIL-TAL1 </it>fusion was validated as a negative prognostic marker in our series of T-ALL.</p

PTEN as a Prognostic and Predictive Marker in Postoperative Radiotherapy for Squamous Cell Cancer of the Head and Neck

BACKGROUND: Tumor suppressor PTEN is known to control a variety of processes related to cell survival, proliferation, and growth. PTEN expression is considered as a prognostic factor in some human neoplasms like breast, prostate, and thyroid cancer. METHODOLOGY/PRINCIPAL FINDINGS: In this study we analyzed the influence of PTEN expression on the outcome of a randomized clinical trial of conventional versus 7-days-a-week postoperative radiotherapy for squamous cell cancer of the head and neck. The patients with cancer of the oral cavity, oropharynx, and larynx were randomized to receive 63 Gy in fractions of 1.8 Gy given 5 days a week (CF) or 7 days a week (p-CAIR). Out of 279 patients enrolled in the study, 147 paraffin blocks were available for an immunohistochemical assessment of PTEN. To evaluate the prognostic value of PTEN expression and the effect of fractionation relative to PTEN, the data on the outcome of a randomized clinical trial were analyzed. Tumors with a high intensity of PTEN staining had significant gain in the loco-regional control (LRC) from p-CAIR (5-year LRC 92.7% vs. 70.8%, for p-CAIR vs. CF, p = 0.016, RR = 0.26). By contrast, tumors with low intensity of PTEN did not gain from p-CAIR (5-year LRC 56.2% vs. 47.2%, p = 0.49, RR = 0.94). The intensity of PTEN highly affected the LRC in a whole group of 147 patients (5-year LRC 80.9% vs. 52.3% for high vs. low PTEN, p = 0.0007, RR = 0.32). In multivariate Cox analysis, including neck node involvement, EGFR, nm23, Ki-67, p53, cyclin D1, tumor site and margins, PTEN remained an independent predictor of LRC (RR = 2.8 p = 0.004). CONCLUSIONS/SIGNIFICANCE: These results suggest that PTEN may serve as a potent prognostic and predictive marker in postoperative radiotherapy for high-risk squamous cell cancer of the head and neck

The subclonal complexity of STIL-TAL1+ T-cell acute lymphoblastic leukaemia

Single-cell genetics were used to interrogate clonal complexity and the sequence of mutational events in STIL-TAL1+ T-ALL. Single-cell multicolour FISH was used to demonstrate that the earliest detectable leukaemia subclone contained the STIL-TAL1 fusion and copy number loss of 9p21.3 (CDKN2A/CDKN2B locus), with other copy number alterations including loss of PTEN occurring as secondary subclonal events. In three cases, multiplex qPCR and phylogenetic analysis were used to produce branching evolutionary trees recapitulating the snapshot history of T-ALL evolution in this leukaemia subtype, which confirmed that mutations in key T-ALL drivers, including NOTCH1 and PTEN, were subclonal and reiterative in distinct subclones. Xenografting confirmed that self-renewing or propagating cells were genetically diverse. These data suggest that the STIL-TAL1 fusion is a likely founder or truncal event. Therapies targeting the TAL1 auto-regulatory complex are worthy of further investigation in T-ALL

Regulation of PTEN by CK2 and Notch1 in primary T-cell acute lymphoblastic leukemia: rationale for combined use of CK2-and gamma-secretase inhibitors

T-cell acute lymphoblastic leukemia (T-ALL) patients frequently display NOTCH1 activating mutations and Notch can transcriptionally down-regulate the tumor suppressor PTEN. However, it is not clear whether NOTCH1 mutations associate with decreased PTEN expression in primary T-ALL. Here, we compared patients with or without NOTCH1 mutations and report that the former presented higher MYC transcript levels and decreased PTEN mRNA expression. We recently showed that T-ALL cells frequently display CK2-mediated PTEN phosphorylation, resulting in PTEN protein stabilization and concomitant functional inactivation. Accordingly, the T-ALL samples analyzed, irrespectively of their NOTCH1 mutational status, expressed significantly higher PTEN protein levels than normal controls. To evaluate the integrated functional impact of Notch transcriptional and CK2 post-translational inactivation of PTEN, we treated T-ALL cells with both the gamma-secretase inhibitor DAFT and the CK2 inhibitors DRB/TBB. Our data suggest that combined use of gamma-secretase and CK2 inhibitors may have therapeutic potential in T-ALL.95467467

Loss of oncogenic Notch1 with resistance to a PI3K inhibitor in T-cell leukaemia

Mutations that deregulate Notch1 and Ras/PI3 kinase/Akt signalling are prevalent in T lineage acute lymphoblastic leukaemia (T-ALL), and often coexist. The PI3 kinase inhibitor GDC-0941 was active against primary T-ALLs from wild-type and Kras(G12D) mice and addition of the MEK inhibitor PD0325901 increased efficacy. Mice invariably relapsed after treatment with drug resistant clones, most of which unexpectedly had reduced levels of activated Notch1 protein, down-regulated many Notch1 target genes, and exhibited cross-resistance to γ secretase inhibitors. Multiple resistant primary T-ALLs that emerged in vivo did not contain somatic Notch1 mutations present in the parental leukaemia. Importantly, resistant clones up-regulated PI3K signalling. Consistent with these data, inhibiting Notch1 activated the PI3K pathway, providing a likely mechanism for selection against oncogenic Notch1 signalling. These studies validate PI3K as a therapeutic target in T-ALL and raise the unexpected possibility that dual inhibition of PI3K and Notch1 signalling could facilitate drug resistance in T-ALL