High-resolution melting analysis for rapid and sensitive NOTCH1 screening in chronic lymphocytic leukemia

High-resolution Melting Analysis for NOTCH1 c.7541-7542delCT Mutation in Chronic Lymphocytic Leukemia: Prognostic Significance in Egyptian Patients

The present study aimed to detect the prevalence of NOTCH1 c.7541-7542delCT mutation in Egyptian CLL patients using HRM assay and to assess its relation to patients' survival. The study included 50 newly diagnosed treatment-naïve CLL patients and 50 age and sex matched healthy controls. NOTCH1 c.7541-7542delCT mutation was detected using High-resolution melting (HRM) assay and direct Sanger sequencing. Outcome parameters included progression free survival (PFS) and overall survival (OS). NOTCH1 c.7541-7542delCT mutation was detected in 5 (10.0%) of CLL patients. No controls had NOTCH1 c.7541-7542delCT mutation. Similar results were obtained by direct Sanger sequencing yielding a sensitivity and specificity of 100.0% for HRM in detection of NOTCH1 c.7541-7542delCT mutation in the studied patients. In univariate analysis, predictors of OS included Trisomy 12, high LDH, presence of NOTCH1 c.7541-7542delCT mutation and lack of CR. In multivariate analysis, only lack of CR was found as a significant predictor of OS. HRM analysis is a sensitive method for detection of NOTCH1 c.7541-7542delCT mutation in CLL patients. This mutation may be linked to poor disease prognosis.

Chidamide inhibits the NOTCH1-MYC signaling axis in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is one of the most dangerous hematological malignancies, with high tumor heterogeneity and poor prognosis. More than 60% of T-ALL patients carry NOTCH1 gene mutations, leading to abnormal expression of downstream target genes and aberrant activation of various signaling pathways. We found that chidamide, an HDAC inhibitor, exerts an antitumor effect on T-ALL cell lines and primary cells including an anti-NOTCH1 activity. In particular, chidamide inhibits the NOTCH1-MYC signaling axis by down-regulating the level of the intracellular form of NOTCH1 (NICD1) as well as MYC, partly through their ubiquitination and degradation by the proteasome pathway. We also report here the preliminary results of our clinical trial supporting that a treatment by chidamide reduces minimal residual disease (MRD) in patients and is well tolerated. Our results highlight the effectiveness and safety of chidamide in the treatment of T-ALL patients, including those with NOTCH1 mutations and open the way to a new therapeutic strategy for these patients.

Comparison of high-resolution melting analysis with direct sequencing for detection of FLT3-TKD, FLT3-ITD and WT1 mutations in acute myeloid leukemia

BACKGROUND

Acute Myeloid Leukemia (AML) is a group of hematologic diseases characterized by a variety of clinically important genetic alterations. Genetic mutations affecting the FMS-like receptor tyrosine kinase-3 (FLT3) and Wilm's tumor (WT-1) genes are associated with poor prognosis in AML. In this work, efficiency of HRM method for detection of FLT3-ITD, FLT3-TKD, and WT-1 mutations was assessed in comparison with direct sequencing.

METHOD

A total of 58 formalin-fixed, paraffin-embedded BM biopsy specimens of AML patients were analyzed. Mutation detection was performed by HRM method and the results were consequently compared with direct sequencing RESULTS: FLT3 and WT-1 mutations were detected in 21 (36.2%) and 3 (5.17%) samples, respectively. Among all FLT3 mutations, 10 (17.2%) and 11 (18.2%) samples were harboring the FLT3-ITD and-TKD gene mutations, respectively. Frequency of the FLT3-ITD was not statistically different in females (51%) and males (49%). Also, FLT3-TKD was more common in males although the differences in gender distribution were not statistically significant (P = 0.721 and P = 0.626, respectively).

CONCLUSIONS

Regarded as the desirable characteristic, the present study is generally distinguished by the similar previous ones due to assessing the FFPE BM tissue from the perspective of the type of assessed sample. This discrepancy between our results and those in prior studies may be due to the disparity of the studied population size, adopted methods as well as the sample type. In this survey, regarding to low amount of extracted DNA from the paraffinized samples, the HRM method was efficient in determining the mentioned mutations.

High-resolution melting analysis for rapid and sensitive MYD88 screening in chronic lymphocytic leukemia

High resolution melting (HRM) assay is a novel technology for the fast, high-throughput, sensitive, post-PCR analysis of genetic mutations. Myeloid differentiation primary response 88 (MYD88) mutations are frequently reported in chronic lymphocytic leukemia (CLL) and confer a worse prognosis. The objective of the present study was to assess the value of HRM analysis for the rapid screening of MYD88 mutations in patients with CLL. Genomic DNA samples were extracted from the bone marrow of 129 newly diagnosed patients with CLL. A plasmid with an MYD88-L265P mutation was constructed, and the p.L265P substitution, which is the predominant MYD88 mutation in CLL, was detected using HRM analysis and direct sequencing. The plasmid pCMV-MYD88-L265P-Mu was successfully constructed as a positive control, and was verified by direct sequencing. The normalized and shifted melting curves of 6/129 (4.65%) samples were clearly different from those of other patients by HRM analysis. In addition, the 794T>C mutation in MYD88 was identified in 6 (4.65%) patients by direct sequencing. Sensitivity evaluation revealed that the HRM assay had a higher sensitivity (to 1% dilution) than direct sequencing, in addition to being convenient and time-saving. The MYD88 p.L256P mutation has been implicated to be associated with adverse prognosis in CLL. HRM analysis has the potential to be a routine prescreening technique to identify the MYD88 p.L256P mutation and may facilitate the clinical treatment of CLL.

NOTCH1 Aberrations in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is an incurable B-cell neoplasm characterized by highly variable clinical outcomes. In recent years, genomic and molecular studies revealed a remarkable heterogeneity in CLL, which mirrored the clinical diversity of this disease. These studies profoundly enhanced our understanding of leukemia cell biology and led to the identification of new biomarkers with potential prognostic and therapeutic significance. Accumulating evidence indicates a key role of deregulated NOTCH1 signaling and NOTCH1 mutations in CLL. This review highlights recent discoveries that improve our understanding of the pathophysiological NOTCH1 signaling in CLL and the clinical impact of NOTCH1 mutations in retrospective and prospective trials. In addition, we discuss the rationale for a therapeutic strategy aiming at inhibiting NOTCH1 signaling in CLL, along with an overview on the currently available NOTCH1-directed approaches.

NOTCH1 mutation and its prognostic significance in Chinese chronic lymphocytic leukemia: a retrospective study of 317 cases

The proto-oncogene NOTCH1 is frequently mutated in around 10% of patients with chronic lymphocytic leukemia (CLL). This study analyzed NOTCH1 mutation status of 317 Chinese patients with CLL by Sanger sequencing. The frequencies of NOTCH1 mutation in the PEST (proline (P), glutamic acid (E), serine (S), threonine (T)-rich protein sequence) domain and the 3' untranslated regions (UTR) were 8.2% and 0.9%, with the most frequent mutation being c.7541_7542delCT and c.*371A>G, respectively. Clinical and biological associations were determined including NOTCH1 mutations with advanced stage (Binet stage, P = 0.010), unmutated immunoglobulin heavy-chain variable region (IGHV) gene (P < 0.001) and trisomy 12 (+12) (P = 0.014). NOTCH1-mutated patients had lower CD20 expression intensity than NOTCH1-unmutated patients (P = 0.029). In addition, NOTCH1-mutated patients had shorter overall survival (OS) (P = 0.002) and treatment-free survival (TFS) (P = 0.002) than NOTCH1-unmutated patients, especially for patients with NOTCH1 c.7541_7542delCT and/or c.*371A>G mutations. Patients with both mutated NOTCH1 and unmutated IGHV had shorter OS (P < 0.001) and TFS (P < 0.001) than those with unmutated NOTCH1 or mutated IGHV. These data provide a comprehensive view of the clinical relevance and prognostic impact of NOTCH1 mutations on Chinese patients with CLL.